mindquantum.algorithm.nisq.quccsd_generator

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mindquantum.algorithm.nisq.quccsd_generator(n_qubits=None, n_electrons=None, anti_hermitian=True, occ_orb=None, vir_orb=None, generalized=False)[source]

Generate qubit-UCCSD (qUCCSD) ansatz using qubit-excitation operators.

Note

Currently, unrestricted version is implemented, i.e., excitations from the same spatial-orbital but with different spins will use distinct variational parameters.

Parameters

  • n_qubits (int) – Number of qubits (spin-orbitals). Default: None.

  • n_electrons (int) – Number of electrons (occupied spin-orbitals). Default: None.

  • anti_hermitian (bool) – Whether to subtract the hermitian conjugate to form anti-Hermitian operators. Default: True.

  • occ_orb (list) – Indices of manually assigned occupied spatial orbitals. Default: None.

  • vir_orb (list) – Indices of manually assigned virtual spatial orbitals. Default: None.

  • generalized (bool) – Whether to use generalized excitations which do not distinguish occupied or virtual orbitals (qUCCGSD). Default: False.

Returns

QubitExcitationOperator, Generator of the qUCCSD operators.

Examples

>>> from mindquantum.algorithm.nisq import quccsd_generator
>>> quccsd_generator()
0
>>> quccsd_generator(4, 2)
-1.0*q_s_0 [Q0^ Q2] +
-1.0*q_s_2 [Q0^ Q3] +
-1.0*q_d_0 [Q1^ Q0^ Q3 Q2] +
-1.0*q_s_1 [Q1^ Q2] +
-1.0*q_s_3 [Q1^ Q3] +
1.0*q_s_0 [Q2^ Q0] +
1.0*q_s_1 [Q2^ Q1] +
1.0*q_s_2 [Q3^ Q0] +
1.0*q_s_3 [Q3^ Q1] +
1.0*q_d_0 [Q3^ Q2^ Q1 Q0]
>>> q_op = quccsd_generator(occ_orb=[0], vir_orb=[1], generalized=True)
>>> q_qubit_op = q_op.to_qubit_operator()
>>> print(str(q_qubit_op)[:315])
0.125*I*q_d_4 + 0.125*I*q_d_7 + 0.125*I*q_d_9 [X0 X1 X2 Y3] +
0.125*I*q_d_4 - 0.125*I*q_d_7 - 0.125*I*q_d_9 [X0 X1 Y2 X3] +
0.25*I*q_d_12 + 0.25*I*q_d_5 + 0.5*I*q_s_0 - 0.5*I*q_s_3 [X0 Y1] +
-0.125*I*q_d_4 + 0.125*I*q_d_7 - 0.125*I*q_d_9 [X0 Y1 X2 X3] +
0.125*I*q_d_4 + 0.125*I*q_d_7 - 0.125*I*q_d_9 [X0 Y1 Y2 Y3] +