28 with T = { 1 , 4 } . On the other hand, all the [[7 , 1 , 7; 6]] EAQEC codes are nondegener- ate codes, while the [[7 , 1 , 5; 3]], [[7 , 1 , 5; 4]],[[7 , 1 , 5; 5]] EAQEC codes can be degenerate or nondegenerate. ✷ In addition, all the [[7 , 1 , 5; 2]] EAQEC codes we found are degenerate codes, for some simplified stabilizer generators are of weight 4 from the check matrix. For example, a sim- plified check matrix and its simplified logical matrix of a [[7 , 1 , 5; 2]] EAQEC code are code. This means that the [[7 , 1 , 5; 2]] and [[7 , 1 , 5; 3]] EAQEC codes cannot be obtained by the construction of [10]. Therefore, the [[7 , 1 , 5; 2]] and [[7 , 1 , 5; 3]] EAQEC codes are new.       $^{0000000}$ 1001011 0000000 1100101 0000000 0010111 1001011 0000000 1100101 0000000 0010111 0000000 1000011 0100011 1101000 0010010       $^{,}$   $^{1001011}$ 0100011 1101000 1001011    , Table 3: Optimization over the [[7 , 1 , 3]] quantum BCH code c d$_{opt}$ d$_{std}$ N$_{opt}$ 2 2 $^{ck}$N ( r, c ) 6 7 5 36 4096 5 5 5 31920 64512 4 5 5 39522 166656 3 5 4 4332 89280 2 5 3 14 10416 1 3 3 252 252