mindquantum.algorithm.error_mitigation.fold_at_random

mindquantum.algorithm.error_mitigation.fold_at_random(circ: Circuit, factor: float, method='locally')[source]

Folding circuit randomly.

Folding a quantum circuit is going to increase the size of quantum circuit, while keeping the unitary matrix of circuit the same. We can implement it by inserting identity circuit after certain gate. For a very simple example, \(RX(1.2 \pi)\) has the same unitary matrix as \(RX(1.2 \pi)RX(-1.2 \pi)RX(1.2 \pi)\), but the size of circuit increase to 3.

Parameters

circ (Circuit) – The quantum circuit that will folding.
factor (float) – Folding factor, should greater than 1.
method (str) – The method for folding. method should be one of 'globally' or 'locally'. 'globally' means we extended circuit is append to the end of circuit while 'locally' means the identity part is randomly added after certain gate.

Examples

>>> from mindquantum.algorithm.error_mitigation import fold_at_random
>>> from mindquantum.core.circuit import Circuit
>>> circ = Circuit().h(0).x(1, 0)
>>> circ
      ┏━━━┓
q0: ──┨ H ┠───■─────
      ┗━━━┛   ┃
            ┏━┻━┓
q1: ────────┨╺╋╸┠───
            ┗━━━┛
>>> fold_at_random(circ, 3)
      ┏━━━┓ ┏━━━┓ ┏━━━┓
q0: ──┨ H ┠─┨ H ┠─┨ H ┠───■─────■─────■─────
      ┗━━━┛ ┗━━━┛ ┗━━━┛   ┃     ┃     ┃
                        ┏━┻━┓ ┏━┻━┓ ┏━┻━┓
q1: ────────────────────┨╺╋╸┠─┨╺╋╸┠─┨╺╋╸┠───
                        ┗━━━┛ ┗━━━┛ ┗━━━┛
>>> fold_at_random(circ, 3, 'globally')
      ┏━━━┓       ┏━━━┓             ┏━━━┓
q0: ──┨ H ┠───■───┨ H ┠───■─────■───┨ H ┠───
      ┗━━━┛   ┃   ┗━━━┛   ┃     ┃   ┗━━━┛
            ┏━┻━┓       ┏━┻━┓ ┏━┻━┓
q1: ────────┨╺╋╸┠───────┨╺╋╸┠─┨╺╋╸┠─────────
            ┗━━━┛       ┗━━━┛ ┗━━━┛