mindquantum.algorithm.nisq.SGAnsatz

class mindquantum.algorithm.nisq.SGAnsatz(nqubits, k, nlayers=1, prefix: str = '', suffix: str = '')[source]

SG ansatz for 1D quantum systems.

The SG ansatz consists of multiple variational quantum circuit blocks, each of which is a parametrized quantum circuit applied to several adjacent qubits. With such a structure, the SG ansatz naturally adapts to quantum many-body problems.

Specifically, for 1D quantum systems, the SG ansatz can efficiently generate any matrix product states with a fixed bond dimension. For 2D systems, the SG ansatz can generate string-bond states.

For more detail, please refers A sequentially generated variational quantum circuit with polynomial complexity.

Parameters

nqubits (int) – Number of qubits in the ansatz.
k (int) – log(R) + 1, where R is the bond dimension of a MPS state.
nlayers (int) – Number of layers in each block. Default: 1.
prefix (str) – The prefix of parameters. Default: ''.
suffix (str) – The suffix of parameters. Default: ''.

Examples

>>> from mindquantum.core.algorithm import SGAnsatz
>>> sg = SGAnsatz(4, 2, 1)
>>> sg.circuit
      ┏━━━━━━━━━━━┓ ┏━━━━━━━━━━━━┓
q0: ──┨ RX(a1_00) ┠─┨ RZ(b1_000) ┠────────■─────────────────────────────────────────────────────────────────────
      ┗━━━━━━━━━━━┛ ┗━━━━━━━━━━━━┛        ┃
      ┏━━━━━━━━━━━━┓               ┏━━━━━━┻━━━━━┓ ┏━━━━━━━━━━━━┓
q1: ──┨ RY(b1_001) ┠───────────────┨ RX(b2_000) ┠─┨ RY(b1_101) ┠────────■───────────────────────────────────────
      ┗━━━━━━━━━━━━┛               ┗━━━━━━━━━━━━┛ ┗━━━━━━━━━━━━┛        ┃
      ┏━━━━━━━━━━━━┓                                             ┏━━━━━━┻━━━━━┓ ┏━━━━━━━━━━━━┓
q2: ──┨ RY(b1_102) ┠─────────────────────────────────────────────┨ RX(b2_101) ┠─┨ RX(b1_202) ┠────────■─────────
      ┗━━━━━━━━━━━━┛                                             ┗━━━━━━━━━━━━┛ ┗━━━━━━━━━━━━┛        ┃
      ┏━━━━━━━━━━━━┓                                                                           ┏━━━━━━┻━━━━━┓
q3: ──┨ RY(b1_203) ┠───────────────────────────────────────────────────────────────────────────┨ RZ(b2_202) ┠───
      ┗━━━━━━━━━━━━┛                                                                           ┗━━━━━━━━━━━━┛