Unitary-transformed projective squeezing: applications for circuit-knitting and state-preparation of non-Gaussian states

作     者：Anai, Keitaro Suzuki, Yasunari Tokunaga, Yuuki Matsuzaki, Yuichiro Takeda, Shuntaro Endo, Suguru 

作者机构：Department of Applied Physics University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-8656 Japan NTT Computer and Data Science Laboratories NTT Corporation Musashino Tokyo180-8585 Japan Department of Electrical Electronic and Communication Engineering Faculty of Science and Engineering Chuo University 1-13-27 Kasuga Bunkyo-ku Tokyo112-8551 Japan 

出 版 物：《arXiv》 (arXiv)

年 卷 期：2024年

核心收录：

主　　题：Qubits 

摘      要：Continuous-variable (CV) quantum computing is a promising candidate for quantum computation because it can utilize infinite-dimensional Hilbert space even with one mode and efficiently handle continuous values. Although the photonic platforms have been considered as a leading platform for CV computation, hybrid systems comprising qubits and bosonic modes, e.g., superconducting hardware, have shown significant developments because they can prepare non-Gaussian state by utilizing the nonlinear interaction between the qubits and the bosonic modes. However, the experimentally realizable size of hybrid hardware is currently restricted. Moreover, the fidelity of the non-Gaussian state is still limited. In this work, by developing the projective squeezing method, we establish the formalism for projecting quantum states onto the states that are unitary-transformed from the squeezed vacuum at the expense of the sampling cost. Based on this formalism, we propose methods for simulating larger quantum devices and projecting the state onto one of the typical non-Gaussian states, the cubic phase state, with a higher squeezing level and higher nonlinearity. For practical implementation, we can apply the smeared projector either by linear-combination-of-unitaries or virtual quantum error detection algorithms by leveraging the interactions in hybrid systems of qubits and bosonic modes. We numerically verify the performance of our methods and also show that the effect of photon-loss errors can be suppressed due to projection. Copyright © 2024, The Authors. All rights reserved.