Квантовые вычисления. Ожигов Ю.С. - 44 стр.

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O(
1
N
) λ
1,2
=
+
2
2i/
N
b =
1
2
1
2
cos
2
2t
N
,
a =
1
2N
sin
2
2t
N
+
1
N
cos
2
2t
N
,
α =
1
2N
cos
2
2t
N
+
1
2N
|O(
1
N
), O(
1
N
), O(
1
N
N
)i b t
1
=
π
N
2
2
b(t
1
) = 1
O(
1
N
) E H
|e
1
, e
2
i 1 O(1/
N)
h
π
N
2
2
i
2
E
1
= |e
1
e
2
i E
2
=
1
N
|e
1
N
2
i E
3
=
1
N
|N
1
N
2
i
E
4
=
1
N
|N
1
e
2
i Z
A
1
=
1
2
N
4
N
2
N
2
N
1
2
N
4
N
4
N
2
N
1
2
N
2
N
4
N
2
N
1
.
χ
2k
χ
2k+1
χ
2k+2
B B
0
= A
2
1
kB
[
π
N
4
2
]
0
|0, 0, 1, 0i
|1, 0, 0, 0ik = O(
1
N
) A
1
O(
1
N
)
¯c
i+1
= B
0
¯c
i
˙
¯c = (B
0
1)¯c, ¯c = ¯c
0
R = exp Bt B = B
0
1
B
4
N
0 1 0 0
1 0 1 0
0 1 0 0
0 0 0 0
O(
1
N
)
¯c H
1
E
1
, E
2
, E
3
D
0
i
2
0
i
2
0
i
2
0
i
2
0
.
B H
1
4
2i
N
D D
2k+1
= D D
2k
= D
2
k =
1, 2, . . . |0, 0, 1i O(
1
N
) k =
4
2
N
O(
1
N
) |b, a, αi C|0, 0, 1i
C = exp(kiDt) = cos(kDt) + i sin(kDt)
= 1
(kDt)
2
2
+
(kDt)
4
4!
. . . + i(kDt
(kDt)
3
3!
+ . . .)
= 1 D
2
(1 cos kt) + iD sin kt
                                                                                        

                    + √    √
O( N1 )   λ1,2 =− 2 2i/ N                          '           )       
                                                        √
                                            1    1     2√ 2t
                                   b   =    2 −  2 cos       ,
                                                       √ N              √
                                   a   =    √ 1 sin 2√ 2t + 1      cos 2√N2t ,                               
                                              2N     √ N       N
                                             1      2√ 2t      1
                                   α =          cos       +
                                        
                                            2N        N       2N
                                                                                                  √
  |O( √1 ), O( 1 ), O( √
                                 1
                                    )i    b         t1 = π2√N  b(t ) = 1
                    N     N     N N                                             2       1
  O( √1 )        E H  )        
                     N
    |e , e i  1 − O(1/√N )  π √N )     
                                                    h √ i
                        1 2
√   )          2        2
                                                           
  2
           E = |e e i  E = √1 |e N i  E = 1 |N N i 
                                                    1      1 2   2   N 1 2      3   N    1 2
E4 = √1N |N1 e2 i   & Z       
                                                                
                                          1    √2      4
                                                           − √2N
                                                 N     N
                                      − √2     1     √2     4   
                                                            N   
                                A1 =  4 N       2
                                                        N
                                                             2   .
                                      N      − √N     1    √
                                                              N
                                                                 
                                           2    4      2
                                         − N
                                          √
                                                N
                                                      √
                                                        N
                                                            −1
   '   #    $   χ −→ χ               −→ χ       
                                                                                 2k       √2k+1 2k+2
                                                                                         π √N
     B      &            B0 = A21     kB0 4 2 |0, 0, 1, 0i −
                                                                                       [      ]

|1, 0, 0, 0ik = O( √1N )           A1      )   O( √1N ) 
      ()    c̄                          c̄˙ = (B − 1)c̄, c̄ = c̄         
                                      i+1 = B0 c̄i                0              0
    R = exp Bt   B = B − 1    
                                0
                                                                   
                                                      0  1 0 0
                                               4  −1 0 1 0 
                                        B≈ √                       
                                                N  0 −1 0 0 
                                                      0  0 0 0
  O( 1 ) 
     *  '  N
                           &  c̄    H '  E , E , E 
                                                                                    1              1 2  3
    D  &
                                                               
                                                 0 − √i2   0
                                            √i      0   − √i2 
                                            2                  .
                                                      i
                                                 0   √
                                                       2
                                                           0
                       B  H1    4√N2i D       D2k+1 = D  D2k = D2  k =
                                             √
    
                                                                                √
1, 2, . . .       |0, 0, 1i   O( √1 )  '  k = 4√ 2    
                                                            N                   N
O( √1N )    |b, a, αi ≈ C|0, 0, 1i  
                        C         = exp(kiDt) = cos(kDt) + i sin(kDt)
                                   (kDt)2       4                         3
                            =1−      2  + (kDt)
                                            4!    − . . . + i(kDt − (kDt)
                                                                      3!    + . . .)
                                     = 1 − D2 (1 − cos kt) + iD sin kt