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Optical conditional spin gates in coupled quantum dots using the electron-hole exchange interaction
We propose a fast optically induced two-qubit c-phase gate between two resident spins in a pair of coupled quantum dots. An excited bound state which extends over the two dots provides an effective electron-electron exchange interaction. The gate is made possible by the electron-hole exchange interaction, which isolates a single transition in the system. When combined with appropriate single qubit rotations, this gate generates an entangled state of the two spins.
I Introduction
Spins in quantum dots (QD) are currently under intense investigation due to their potential use as bits of quantum information. All-optically controlled QDs are particularly attractive, as they take advantage of the speed at which optical transitions can be accessed with high degree of control. Qubit operations are typically realized through Raman-like transitions via optical generation of an electron-hole pair. Thus far, many of the requirements of quantum computation have been demonstrated experimentally in QD systems: initialization,Xu et al. (2007) readout,Atatüre et al. (2007); Mikkelsen et al. (2007) and long coherence times,Greilich et al. (2006a) as well as some recent advances in single-qubit control.Mikkelsen et al. (2008); Ramsay et al. (2008) Recently conditional control between a spin and an exciton qubit was demonstrated in coupled QDs.Robledo et al. (2008) However, two-qubit gates between spins, which are necessary for spin-based quantum computation, are yet to be realized in those systems. Such gates are conditional, i.e., they alter the state of the one qubit depending on the state of the other. For such an operation, the ability to switch on an interaction between the two qubits is required. Proposals for optical two-spin gates have been made using a cavity photon modeImamoğlu et al. (1999); Clark et al. (2007) or using optical excitation of electron-hole pairs Piermarocchi et al. (2002); Nazir et al. (2004); Lovett et al. (2005); Calarco et al. (2003); Emary and Sham (2007) as mechanisms for this interaction.
In this work we consider an approach where the intermediate electron is in an excited bound state that extends over both dots. Such states have the advantage of weaker coupling to the continuum, and they have been studied experimentally.Stinaff et al. (2006) Our scheme is general enough to cover both vertically stacked coupled QDs, and also laterally coupled QDs.Wang et al. (2006); Beirne et al. (2006) The latter are thought to be desirable for a scalable quantum computing architecture, in which vertically coupled QDs would be used to encode logical qubits in multiple physical qubits, so that quantum error correction is possible. A sketch of the QD potential and of the single-particle states is shown in Fig. 1(a) for the vertically coupled QDs and in 1(b) for the laterally coupled ones. In the insets, the relevant orbital electronic states are shown schematically: and are the states localized within each QD, and is an extended state mediating the exchange interaction. The requirement that the qubits are uncoupled in their ground state (and addressable separately) while there exist transitions that allow for their coupling has been shown experimentally for vertical QDs;Stinaff et al. (2006) in that case coupling is achieved in the excited state by an external electrical bias that brings a certain excited state in resonance, so that the electron of the optically generated exciton is in a molecular state of the two dots. For lateral dots, this requirement can be met if the potential along the line coupling the two QDs has the shape of an asymmetric mexican hat, an attractive potential with two asymmetric minima. The asymmetry could represent differences of size and composition between the two QDs, and it prevents the electrons in the ground states from tunneling into the other dot. As the energy quantum number is increased the states become more extended while still bound in the two QDs.
The key component of our proposal is use of the electron-hole exchange interaction (EHEI), which has not been considered previously in conditional gate designs. EHEI gives rise to well-known features of QDs, such as the splitting between optically active (bright) and optically inactive (dark) excitons, as well as the splitting of the bright exciton doublet, which results in the linearly polarized photoluminescence of neutral QDs. These effects are crucial in the role of QDs as entangled photon emitters,Akopian et al. (2006); Greilich et al. (2006b) and they have been studied extensively in recent years.Urbaszek et al. (2003); Finley et al. (2002); Seguin et al. (2005); Ediger et al. (2007); Poem et al. (2007)
EHEI can play a significant role in optically controlled spin qubits, depending on the number of electrons in the intermediate optically excited state. For an even number of electrons the total electron spin can be zero, in which case there is no net EHEI. On the other hand, a state with an odd number of electrons always has half integer, i.e., nonzero total spin, which means nonzero net EHEI. Here we show that in the case of a two-spin conditional gate, where the intermediate state contains 3 electrons and one hole, the nonzero EHEI allows for a simple and fast design of a c-phase gate.
II Three-electron states
The system we consider involves two resident electrons in two coupled QDs. The growth axis of the QDs defines the axis and is also the optical axis, and an external magnetic field along the perpendicular direction defines the axis (Voigt geometry). Upon optical excitation, the system consists of three electrons and one hole. The exchange interaction between the same quasi-particles (electron-electron) is the strongest interaction, on the order of 2-6 meV.Scheibner et al. (2007) First we diagonalize the e-e exchange interaction in the three single particle basis states illustrated in Fig. 1, . Then the states diagonalizing the e-e exchange Hamiltonian are eigenstates of the total electron spin , which can be , and the projection of that spin along the quantization axis.
The quadruplet is separable in spin and orbit, so it is straightforward to write it down as a product of the antisymmetric orbital state and the symmetric spin state: , where and . The energy of the states at zero field is , where () is the exchange integral between electrons in states and (), and is the energy of the three particles including direct Coulomb terms. The e-e exchange term between states and is essentially zero, and it has been dropped.
The remaining sets of states both have . To find their energies and express them in terms of single particle states, we use the basis states , (where stands for cyclic permutations) for the states. The Coulomb interaction does not mix different spin projections, so we diagonalize each spin projection subspace separately. The Hamiltonian in the basis is
(4) |
Diagonalizing the above Hamiltonian gives the following eigenstates
with normalization (for the basis states all the spins are flipped). We label the states by their energies, , as , where is the spin projection along the quantization axis. In the following we take .
III Inclusion of electron-hole exchange interaction
Now we consider the hole. The two heavy hole states in the QD act as a pseudospin and split in the presence of the magnetic field.Xu et al. (2007) Taking the tensor product of these with the three-electron states above gives a total of sixteen non-degenerate basis states. The exchange interaction between an electron labeled by and the hole is anisotropic, and can be written in terms of the hole pseudospin and the electron spin as Bayer et al. (2002)
(5) |
where is an operator acting on the envelope functions of the electron and the hole and is different for each of the principal axes.Bayer et al. (2002) It can be shown that , where are electron and hole envelope states respectively. These terms are responsible for the familiar anisotropic exchange between bright excitons in the -shell. is responsible for the splitting between bright and dark excitons. The full exchange Hamiltonian is given by the sum of three terms of the form (5), one term for each electron. In the presence of a magnetic field, the full four-particle Hamiltonian can be expressed as
(6) | |||||
The terms in the first two lines conserve the total electron spin . The terms in the last line are spin-antisymmetric and mix states of different total electron spin.
The Hamiltonian (6) is invariant under parity transformation, which means that , where is the operator that rotates the total () spin about the quantization axis by angle . The Hamiltonian is therefore block diagonal according to the parity eigenvalue: The states of even parity, {}, are labeled by , and the states of odd parity, {}, are labeled by . Therefore the Hamiltonian splits in two blocks. The energy levels are shown in panel (a) of Fig. 2 without EHEI, while panel (b) includes EHEI, with typical values taken from experiment and Zeeman splittings corresponding to about 8 T. The orange color represents states of odd parity, while the green those of even parity. From the figure, one can see that the levels become mixed and shifted by the EHEI, with the mixing occurring predominantly within the same total electron spin multiplets. This is because the electron-electron exchange is much larger than the EHEI. It is therefore an appropriate approximation to ignore the spin-mixing terms in Eq. (6) and take to be a good quantum number. In the following we will focus on the topmost four states (dashed box in Fig. 2(b)), and use them for our gate design.
The Hamiltonian in this space is block diagonal, consisting of one block in the even subspace and one in the odd subspace . Diagonalizing each block gives the four eigenenergies
where , .
Now we also consider the qubit subspace, shown at the bottom of Fig. 3(a) and (b), and corresponding to the two spins in the two QDs before optical excitation. The optical selection rules between this qubit subspace and the four states from Fig. 2 are such that -polarized light couples even to even and odd to odd states, whereas polarization couples odd with even states. These can be derived from the well-known circular selection rules if our basis states are expressed as linear combinations of the spin states polarized along the growth axis. They have also been demonstrated experimentally.Xu et al. (2007) First, let us ignore EHEI (Fig. 3(a)): then, not all ground states couple to every excited state. For example, the transition from the two-qubit state to the lowest state of the quadruplet, is optically forbidden, as indicated in Fig. 3(a). To implement a c-phase gate optically, a transition has to be addressed between (or ) and an excited state, without other transitions being excited. However, in the absence of EHEI, each transition has a frequency and polarization that is doubly degenerate. An example is shown in Fig. 3(a), for the two transitions labeled by their common frequency, . This means that the target transition cannot be isolated, irrespective of the laser bandwidth and polarization.
Now, we include EHEI, in panel (b) of Fig. 3. The transition between and the lowest excited state now is allowed, and moreover it has a unique frequency. This transition is enabled by the EHEI. Stronger EHEI results in a larger dipole moment for this transition and larger energy separation from the nearest transition. This can be seen in Fig. 3, panels (c) and (d), where the dipole and detuning are plotted as functions of the isotropic and anisotropic EHEI between the hole state and the electronic state , and . Here the hole has been taken to be confined within one QD (the one with state ), so the EHEI with state is zero; for state we have taken and . The range of values for the EHEI shown in Fig. 3(c),(d) is taken from experiments.Bayer et al. (2002); Finley et al. (2002); Scheibner et al. (2007); Poem et al. (2007)
IV Two-qubit c-phase gate
For the 2-qubit gate, we propose using a laser of pulse area 2 resonant with the transition discussed above (thick arrow in Fig. 3(b)). The pulse can have any temporal shape, and its effect will be to induce a minus sign to the state, leaving the rest of the basis states unaffected, i.e. it can be expressed by the unitary . This is the c-phase quantum gate, which we denote by . The result that inclusion of EHEI makes possible this 2-qubit gate is remarkable, since EHEI is usually viewed as a source of decoherence and error.
Our c-phase gate is compatible with the single qubit gates that we developed earlier,Economou and Reinecke (2007) since the two QDs have optical excitations at different frequencies (about 10 meV apart), so the speed of the single qubit gates is not compromised. These single spin gates, implemented through the lowest trion localized in each QD, in combination with the present c-phase gate, provide the entangling cnot gate as , where is the single qubit operator representing a rotation by angle about axis . Single qubit rotations about have picosecond durations,Economou et al. (2006) so the total gate time is not slowed down by the single-qubit gates.
We have performed numerical calculations in the space of Fig. 3(b) to simulate the c-phase gate in the presence of decoherence and relaxation dynamics. The fidelity has been calculated as the average Emerson et al. (2005)
(7) |
where , is the ideal operation, and is the actual operation. The indices run through all four possible two-qubit states. The predominant dissipation mechanisms are relaxation to lower levels and spontaneous emission of the trion (recombination). We have used an effective recombination rate in the Lindblad master equations to account for both of these mechanisms. In those simulations we used the following values for the parameters: for the Zeeman splittings meV, meV, which corresponds to a field of about 8 T for InAs QDs. For the EHEI we used the recently measured values by Poem et al.,Poem et al. (2007) meV, meV, meV, . We have used a gaussian pulse envelope, , with meV, shown in the inset of Fig. 4. Fig. 4 shows the calculated fidelity for varying values of : the fidelity ranges from 79% for ps to about 94% for ps.
We note that the values of the EHEI used in our calculations were chosen for concreteness, and our proposal is valid for a wide range of EHEI values. Stronger EHEI is advantageous, as it better isolates the target transition from the other transition, Fig. 3(d), leading to higher fidelity and shorter gate times.
V Conclusions
In conclusion, we have proposed an optically induced c-phase gate between spins in neighboring (coupled) QDs. This gate, in combination with our single qubit rotations, is equivalent to the familiar c-not gate. Our proposal yields fidelities on the order of 85% for gates of pulsewidth of about 100 ps. The electron-hole exchange interaction has been shown to be a crucial component of this conditional control by isolating a transition in the system, thereby making the gate possible.
We thank S.C. Badescu for useful discussions. This work is supported by the US Office of Naval Research. One of us (S.E.E.) is an NRC/NRL Research Associate.References
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While traveling the suburbs of Birmingham, Alabama, you will find a city where everyone wants to live.
It is a city so safe and peaceful that it has the eighth-lowest crime rate in the country.
In 2007, Business Week named it the 13th "Best Place to Raise Your Kids."
In the same year, Money magazine listed in the "Top 100 Best Places to Live in the U.S."
This city is none other than the city of Helena in Alabama!
However, Helena's safety is not its only strong suit.
This city also offers a wealth of exciting recreation, a breathtaking environment, and vibrant culture.
Its natural parks, exciting festivals and traditions, diverse cuisine, and entertaining attractions might make you consider moving there.
Check out the best things to do in Helena, Alabama.
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After a joyful day touring the city, take a laidback stroll around the city center of Helena.
You can walk along the famous creek of the city, Buck Creek, and see the mini waterfall in Helena Park.
The relaxed and friendly ambiance will surely calm you, and the night lights along the road give a magnificent view.
You can also see boutiques and stores along the street or dine and hang out at the famous food and pub chain, Beef O' Brady's.
Bring your travel buddies for a walk around the Helena City Center.
See more of the city and meet friendly locals along the way.
Checking out this majestic haven on the city's outskirts is a must for an excellent start to your vacation in Helena.
Campers enjoy the homey nature ambiance with a nice view of Cherokee Beach Lake at the Cherokee Campground and RV Park.
Although the lake prohibits swimming, visitors can enjoy fishing from the bank.
The grounds are blissful and tidy, complete with amenities and well-kept trails.
You can also find good spots for hanging out and enjoying a picnic.
Even for a night or a few days, your stay at the Cherokee Campground and RV Park will be one of your most relaxing experiences.
Even though the city of Helena is not as big as other metropolises, it holds an exciting and colorful history worth revisiting.
The Kenneth R. Penhale City of Helena Museum features artifacts that have shaped the beloved city, such as coal mining and steel manufacturing.
You will also hear stories from the Civil War.
During the Civil War, Helena became an industrial capital thanks to the railroad connecting it to other bigger neighboring towns in the Confederacy.
The museum also exhibits how the city overcame tragedies such as the Great Depression and the 1933 tornado.
The resilience of the city of Helena is in the museum's walls, inspiring every visitor in the museum.
The city of Helena enjoys good agricultural lands suitable for farming.
Residents take the initiative to showcase their harvest and products during the most-awaited Helena Market Days.
This event occurs every year on Saturdays from the first weekend of June to the last weekend of August.
People flock to the Amphitheater Park on Helena Road to check the yields and products.
You can buy fresh vegetables and fruits, bread, jams and spreads, baked goodies, and special delicacies.
The Helena Market Days are an excellent chance to taste what the city offers, mingle with other residents, and support the local farmers and producers.
You do not have to go far to look for the freshest food products because Helena has it all for you!
With the diversity of cuisines in the Birmingham area, it is hard not to crave good old American grub that tastes like home.
The Depot Deli and Grill will satisfy your longing for American comfort food.
This deli serves terrific burgers, mouthwatering grilled and specialty sandwiches, and delicious hotdogs.
You can also order classic American plates that will surely take your taste buds to greater heights.
Enjoy your meal amid the fresh air and a nice view from the waterfront patio facing the Buck Creek of Helena.
Every bite is a piece of comfort from the Depot Deli and Grill in the heart of Old Town Helena.
Remember when you received a remote control car and raced it with your friends?
Who would have thought you could feel that way again at Warehouse Hobby Raceway?
Tthis place has an off-road race track where you can play with your RC cars or join a racing game or tournament.
Whether you are a child or not, you will indeed have a great time as you bond with other players of all ages to enjoy friendly competition.
The Warehouse Hobby Raceway has complete facilities and amenities to make sure your visit will be worth your time.
Every year, the city of Helena celebrates a weekend festival that you should never miss.
This event aims to raise money for charities and future endeavors and projects of the city.
The Buck Creek Festival does not run out of exciting activities and events.
One of them is the most-awaited Duck Race, where people release thousands of rubber ducks from the water dam.
Watch the ducks go down the falls and into the nets!
Listen to live music performances and eat good food at the festival.
Artists and vendors from around the region come and join in the city-wide celebration.
Bring your family and friends and play many fun games on the playground.
Without a doubt, joining the Buck Creek Festival eases the heart.
Have fun and enjoy the festival to support a good cause and mission.
Goodfellas Social Club is a fantastic bar where you can find high-quality drinks and a laidback ambiance for meetups with friends.
This cozy bar on Helena Road offers high-end whiskeys, premium spirits and cocktails, and various wines from around the world.
You can also order heartwarming regional and local beers.
With that number of options, you might find it hard to choose your drink for the night.
Its vintage vibe and old-school decor complement its good food.
Likewise, the bar has a separate smoking lounge.
The night is always young at Goodfellas Social Club, so enjoy your visit and the relaxing atmosphere of the pub.
It is everyone's ultimate dream to ride a hot air balloon and see the ground from the skies.
You can finally try it at Southern Balloon Journeys in Helena!
Fall in love with the aerial views as you travel above the towering buildings of the metropolitan area of Birmingham and across the neighboring cities.
You will also see the country's beautiful farmlands, incredible parks and natural attractions, and majestic rivers from afar.
During this high-altitude adventure, you will feel like the king or queen of the world, looking down on your dominion.
Visit Southern Balloon Journeys with your friends and family.
Cross off the hot air balloon ride from your bucket list!
Joe Tucker Park is the best place to enjoy an outdoor casual family gathering.
This park has vast playgrounds for the kids to run around and play with other children.
It also has baseball fields and tennis courts for sporty older children and adults.
If you want a more relaxed activity, you can also enjoy fishing at the pond or strolling around the pristine walking trails of the park.
The park is also rich in flora and fauna in its natural habitat.
Spot the geese, ducks, and turtles around the area.
Enjoy a memorable day with your family with all the different activities you can do at Joe Tucker Park.
Do you want to meet farm animals and experience life on a farm?
Then, mark Helena Hollow on your map because you won't regret visiting this farm.
Helena Hollow is an entertainment farm where you can book activity spots like the party barn.
Likewise, you can interact with different farm animals such as llamas, goats, horses, cows, and more.
You can also go to the marina, enjoy the sandy beach, or try fishing in the lake.
Visitors can also book the nerf battleground to enjoy a friendly nerf battle complete with gear and amenities.
However, the farm's centerpiece is its pumpkin patch.
Visitors from all over the state come during the peak month of October to check out and buy pumpkins.
With all the fun things to do, Helena Hollow embodies the meaning of entertainment.
Nothing compares to traditional and authentic Mexican food served hot and fresh.
The El Patron Bar & Grill satisfies your Mexican food cravings with their flavorful dishes, drinks, and snacks that will fill you up.
Order their burritos, quesadillas, enchiladas, fajitas, and tacos.
The El Patron Bar & Grill also prepares these Mexican classics in different varieties but with bursting and appealing flavors.
You can pair these meals perfectly with your favorite Mexican dips, sides, drinks, and alcoholic beverages.
This budget-friendly Mexican feast is worth your time.
Bring your travel buddies and see why you don't have to visit Mexico to enjoy their cuisine.
El Patron Bar & Grill will bring the taste of Mexico to you!
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Oak Mountain State Park is a 9,940-acre state park with hiking trails, stunning natural landscapes, campgrounds, lakes, and a wildlife center.
It also has attractions that will make your visit an all-around escapade.
You can find it in Pelham, Alabama, 18 minutes from Helena.
Visitors come mostly to do hiking, camping, and mountain biking.
Many visitors don't even know that you can do many other activities at the park.
Oak Mountain State Park also has a golf course, an archery range, a farm, fishing spots, horseback riding, and beautiful beaches.
Playgrounds are also open for people to enjoy and make the most of their park visit.
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People always stop by here whenever they visit the cities surrounding the Birmingham area.
Bring your family or friends and create good memories at Oak Mountain State Park.
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Martin Lewison from Forest Hills, NY, U.S.A., CC BY-SA 2.0, via Wikimedia Commons
Driving for 27 minutes from Helena will take you to Bessemer, Alabama.
Bessemer contains twin parks that are heaven on Earth for adventure-seekers.
These are the Alabama Adventure & Splash Adventure Water Parks.
They feature thrilling rides like roller coasters, swinging rides, a drop zone, and exciting laser maze challenges.
On the other hand, the water park also packs a lot of splashing fun with its wave pool, soaring and twisting slides, and a splash maze.
Martin Lewison, CC BY-SA 2.0, via Wikimedia Commons
You can swim, cool down, and enjoy the lazy river or the expansive pools.
Guests of all ages can never have enough fun with all the incredible slides and rides at the Alabama Adventure Amusement Park and Splash Adventure Water Park.
Felix Mizioznikov / Shutterstock.com
Meeting animals is always an event many look forward to!
The Birmingham Zoo is home to about 180 species of animals.
You can find it in Birmingham, Alabama, 25 minutes from Helena.
Children will indeed feel excited as they meet several animal species such as the African elephant, Aldabra tortoise, red panda, African lion, North American black bear, reticulated giraffe, and more.
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The zoo dedicates itself to animal conservation and provides care and comfort to its animals.
They want the animals to live comfortably and happily in their natural habitats within the zoo.
In addition to being a conducive learning environment, the zoo also hosts several educational programs and camps.
These are excellent opportunities for students and kids to examine the lives of these animals and how people can take care of them.
The Birmingham Zoo is a popular destination with a good mission and causes worth supporting.
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You should embark on an adventure around Helena at least once in your life.
Likewise, you may realize that Helena is not only one of the best places to live but is also one of the most fun places to visit.
Book your trip today and discover the best things to do in Helena!
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Cummer Logo V-Neck T-Shirt
A Cummer Museum exclusive, this heather grey tee features the Cummer brand mark on the front with the full Museum logo on the back.
This updated essential unisex jersey t shirt fits like a well-loved favorite, featuring a classic V-neck, short sleeves and superior combed and ring-spun cotton.
90% combed and ring-spun cotton, 10% poly
Fashion Fitting


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I would request that VEX post more detailed release notes for the cortex and joystick firmware. CMU has just released ROBOTC V3.05 which includes master firmware version 3.20. We have had success over the last three months with the V3.16 firmware included with ROBOTC version 3.04 and EasyC version 18.104.22.168, the common firmware between these two development environments has simplified switching back and forth at will.
Is V3.20 in any way compatible with V3.16? ie. can a joystick on one version communicate with a cortex on a different version?
Upgrading multiple cortex and joystick systems in a school environment is time consuming. More detailed release notes explaining exactly what has changed in the firmware would allow a more objective decision to be made as to the necessity to upgrade. We prefer to delay but obviously if there are improvements to firmware stability then we would like to know about these.
Any details you can provide would be appreciated.


text: Const Projects Details 3D Design Details About Metal Maison was formed in 2008 with the goal of providing imaginative architectural and construction solutions within the economic and developmental constraints of all clients. The firm believes that all projects benefit from a process involving the client, architect, builder and other specialists in a formative collaboration, and the successful projects are made possible through the management of all participants involved The partners Metal Maison have over twenty years of experience working on complex projects ranging from private villa, restaurants, gym, residential buildings, etc. Through this experience, the firm has developed a sophisticated and thorough approach to design and technical development.


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Mild antiseptic hand cleansing gel with moisturizing agents such as Vitamin E, Panthenol and Aloe.
Instant hand cleaning and care, without water and soap.
Contains 70% Ethyl alcohol. The unique combination of Vitamin E, Aloe and Panthenol moisturizes and protects the skin from irritation and dryness.
Ideal for office, school and public places. With mild fragrance.
Contains 70% Alcohol, Vitamin E, Aloe and Panthenol
Alcohol Denat, Aqua, Glycerin, Panthenol, Aloe Barbadensis Leaf Juice, Tocopheryl Acetate, Mannitol, Cellulose, Hydroxypropyl Methylcellulose, Polyacrylate Crosspolymer-11, Glyceryl Caprate, Citric Acid, Parfum, CI 42051.
Apply on dry hands and rub until it's dry.
Precautions: Keep away from children. Avoid eye contact. For external use only.
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Product with a mechanism of winding and lowering the canvas, by gearbox and crank. It can be made in..
The awning is a self-stretching structure in a rectangular shape, without a drive mechanism. It crea..
Octagonal umbrella - a solution for reliable sun shading, easy and convenient operation. Its constru..
The product model Venezia Z is a vertical blind with PVC transparent film, a protective aluminum box..
Pergola consists of aluminum profiles with a hard lamella roof (works on the principal of jalousie),..
The awning is a self-stretching structure in a perfectly round shape, without a drive mechanism. It ..
Umbrosa is one of the best Belgian companies focused on production of designer sun protection produc..


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In the last year, the coronavirus pandemic has required local governments to innovate in how we engage and interact with the people we represent and serve.
This included moving all public meetings online and, as a result, watching the number of people observing and participating in those meetings increase exponentially. With easy access to their local government, more people than ever are engaged and following local decision-making, and that is good for government and the public.
In Salem, we saw a 700 percent increase in public attendance at our public hearings after going virtual last spring, with public attendance at times exceeding the number we could legally fit inside the City Council chambers pre-pandemic.
These days, there is a lot at stake in those meetings that impacts our daily lives, from public health decisions to school reopenings and more.
Massachusetts residents want and deserve to have that same access to their state government. If 351 cities and towns can adopt budgets, engage in policy debates, hire and evaluate staff, and create local laws — all while meeting the rightly rigorous standards of the Commonwealth's Open Meeting Law — there is no valid reason why our state colleagues cannot do the same.
The Open Meeting Law helps hold all elected officials more accountable. There have been times when a board or committee in Salem, including ones that I chair, has inadvertently skipped a step in posting an agenda or accepting minutes of a meeting. We have been justifiably corrected on those mistakes by vigilant residents or the media. And that has helped make our process even more transparent and more accountable. In other words, sunlight made us better.
Providing consistent access to legislative committee meetings, agendas, minutes, votes, and debates would showcase the quality of our public officials' deliberations and the strength of their arguments — pro or con. It would also demonstrate the hard work and diligence regularly undertaken by so many public servants in state government.
We have strong, talented leaders in both the House and Senate. They have ushered in impressive legislative victories for the people they serve — on climate change, COVID-19 relief, public safety reform, balanced budgets, transportation, and infrastructure.
Allowing more of the public to observe the workings of state government enables every resident to more fully understand and appreciate the complexity of the issues before the state, the challenges and nuances of advancing important legislation, and the reasoning behind the arguments for or against that legislation. It offers a chance for residents to be persuaded or learn more about issues of great importance to them and provides legislators with insights, input, and suggestions from constituents following a policy or legislative debate.
Even during this pandemic, local leaders and the thousands of volunteers serving on boards and commissions pivoted to ensure residents had online access to our discussions. And it worked. The collective use of virtual meeting tools by so many Massachusetts residents has made it easier for residents of all ages to engage on issues they care about without having to drive to a hearing at city hall or hire a babysitter to attend a school committee meeting. They took part in the democratic process and they could do so from the comfort of their own homes.
There is so much that we've lost as a result of this pandemic, but one thing we've gained is the ability to connect and engage at work, in school, with family, and in government in new and different ways. Let's not go backward.
Massachusetts should afford the same level of access, awareness, and accountability to the governing process on Beacon Hill as is required of the 351 cities and towns — and the thousands of city councils, school boards, and local committees — that make up the Commonwealth's municipal governments.
We are one of just 11 states whose public meeting laws expressly exclude its state legislature. We are better than that. And we should not hesitate to prove it.
Kim Driscoll is the mayor of Salem.


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RAINBOW's represent the latest evolution in inverter technology DC welding equipment. These powerful 100 KHz power sources are based on latest generation IGBT's and fitted with a flat transformer. RAINBOW's, with their lightness, reduced size and their excellent
characteristics in electrode MMA and TIG welding with "Lift" mode arc striking, are the most suitable solution for maintenance and light fabrication works. RAINBOW 153 CELL and 183 CELL VRD are special versions for cellulosic electrodes.
- Superior exceptionally high welding characteristics with any type of electrode
- Three available welding processes
- Possibility to work with adequate size power generator sets.
- Low energy consumption and high electrical efficiency
- All the data are referred to 40deg C environment temperature
- Suitable to be used with 100 m length cable without power loss
- Shock-proof fibre compound main structure with protected control panel
- Dust-proof electronic components, thanks to the innovative �Tunnel� fan cooling system, allow its use in the toughest work environments
(Here Is The Product's Brochure Pdf File.)
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Panasonic AG-ES10
image by M Styborski (Image rights) |
Panasonic introduced the AG-ES10 in about 1988, as one of the first wave of "filmless, electronic" cameras. But like other still-video cameras of the era, this was not a digital camera; it recorded analog TV scan lines onto special 2" Video Floppy disks. A floppy could store 25 images in "frame" mode and 50 in "field" mode (where every other video scan line was skipped).
The AG-ES10 is quite similar to the Canon RC-470, although with different styling and top panel controls. The AG-ES10 used a 1/2"-format CCD sensor of about 360,000 pixels. There was a switchable dual-focal-length lens, giving a 35mm equivalent coverage of 48 or 86 mm. The list price in 1991 was stated to be USD $1,650[1], which translated into 2012 dollars would equal about $2,750[2].
Similar to Sony who would later release the digital versions of Mavica cameras that use High Density floppy disc, Panasonic also released a digital version called PV-SD4090, that uses SuperDisc, which was also compatible with HD floppy disc.
- ↑ "17 Top Electronic Cameras," December 1991 Popular Photography (Vol. 98, No. 12; page 109).
- ↑ Inflation adjustment from US Dept. of Labor, Bureau of Labor statistics CPI Inflation Calculator.
Back view showing floppy drive opened image by M Styborski (Image rights) |