Assisted quantum simulation of open quantum systems

• Published in: iScience 2023-04, Vol.26 (4), p.106306-106306, Article 106306
• Main Authors: Liang, Jin-Min, Lv, Qiao-Qiao, Wang, Zhi-Xi, Fei, Shao-Ming
• Format: Article
• Language: English
• Subjects: Quantum mechanics; Quantum physics; Quantum theory
• ISSN: 2589-0042; 2589-0042
• DOI: 10.1016/j.isci.2023.106306

Universal quantum algorithms (UQA) implemented on fault-tolerant quantum computers are expected to achieve an exponential speedup over classical counterparts. However, the deep quantum circuits make the UQA implausible in the current era. With only the noisy intermediate-scale quantum (NISQ) devices in hand, we introduce the quantum-assisted quantum algorithm, which reduces the circuit depth of UQA via NISQ technology. Based on this framework, we present two quantum-assisted quantum algorithms for simulating open quantum systems, which utilize two parameterized quantum circuits to achieve a short-time evolution. We propose a variational quantum state preparation method, as a subroutine to prepare the ancillary state, for loading a classical vector into a quantum state with a shallow quantum circuit and logarithmic number of qubits. We demonstrate numerically our approaches for a two-level system with an amplitude damping channel and an open version of the dissipative transverse field Ising model on two sites. [Display omitted] •A quantum-assisted quantum algorithm framework is introduced and analyzed•A hybrid quantum-classical algorithm for amplitude encoding is proposed•The quantum-assisted quantum simulation of open quantum systems is presented Quantum theory; Quantum physics; Quantum mechanics