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Restoring broken symmetries using quantum search “oracles”

2023; American Physical Society; Volume: 107; Issue: 3 Linguagem: Inglês

10.1103/physrevc.107.034310

2470-0002

Edgar Andres Ruiz Guzman, Denis Lacroix,

Quantum and electron transport phenomena

We present a new method to perform variation after projection in many-body systems on quantum computers that does not require performing explicit projection. The technique employs the notion of ``oracle'', generally used in quantum search algorithms. We show how to construct the oracle and the projector associated with a symmetry operator. The procedure is illustrated for the parity, particle number, and total spin symmetries. The oracle is used to restore symmetry by indirect measurements using a single ancillary qubit. An illustration of the technique is made to obtain the approximate ground state energy for the pairing model Hamiltonian.