Abstract
Exceptional points (EPs), the degeneracy points of non-Hermitian systems, have recently attracted great attention because of their potential of enhancing the sensitivity of quantum sensors. Unlike the usual degeneracies in Hermitian systems, at EPs, both the eigenenergies and eigenvectors coalesce. Although EPs have been widely explored, the range of EPs studied is largely limited by the underlying systems, for instance, higher-order EPs are hard to achieve. Here we propose an extendable method to simulate non-Hermitian systems and study EPs with quantum circuits. The system is inherently parity-time (PT) broken due to the non-symmetric controlling effects of the circuit. Inspired by the quantum Zeno effect, the circuit structure guarantees the success rate of the post-selection. A sample circuit is implemented in a quantum programming framework, and the phase transition at EP is demonstrated. Considering the scalable and flexible nature of quantum circuits, our model is capable of simulating large-scale systems with higher-order EPs.
Highlights
Exceptional points (EPs), the degeneracy points of non-Hermitian systems, have recently attracted great attention because of their potential of enhancing the sensitivity of quantum sensors
We propose a realization of non-Hermitian system to study EPs using the quantum circuits, which is applicable to noisy intermediate-scale quantum (NISQ) devices
Since the measurement on ancilla is repeated in the same basis, similar to the quantum Zeno effect, the success rate can be boosted by dividing each unit to smaller units
Summary
Exceptional points (EPs), the degeneracy points of non-Hermitian systems, have recently attracted great attention because of their potential of enhancing the sensitivity of quantum sensors. Considering the scalable and flexible nature of quantum circuits, our model is capable of simulating large-scale systems with higher-order EPs. Quantum computation is long believed to be faster than the classical counterpart for many tasks. The power of the fast developing quantum computing is largely ignored in the study of simulating non-Hermitian systems and investigating EPs. Here we propose a realization of non-Hermitian system to study EPs using the quantum circuits, which is applicable to noisy intermediate-scale quantum (NISQ) devices. It is straightforward to generalize the method to multi-qubit systems and higher-order EPs. We expect that the quantum chips in the near future could outperform the classical simulators for large non-Hermitian systems. We believe this work paves the way for simulating non-Hermitian physics and investigating EPs with quantum computers
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