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It is difficult to calculate the energy levels and eigenstates of a large physical system on a classical computer because of the exponentially growing size of the Hilbert space. In this work, we experimentally demonstrate a quantum…

Quantum Physics · Physics 2019-03-12 Zhaokai Li , Xiaomei Liu , Hefeng Wang , Sahel Ashhab , Jiangyu Cui , Hongwei Chen , Xinhua Peng , Jiangfeng Du

Eigenvalue transformations appear ubiquitously in scientific computation, ranging from matrix polynomials to differential equations, and are beyond the reach of the quantum singular value transformation framework. In this work, we study the…

Quantum Physics · Physics 2026-01-27 Shan Jiang , Dong An

Currently available quantum hardware allows for small scale implementations of quantum machine learning algorithms. Such experiments aid the search for applications of quantum computers by benchmarking the near-term feasibility of candidate…

Quantum Physics · Physics 2021-09-08 Michael R. Geller , Zoë Holmes , Patrick J. Coles , Andrew Sornborger

The accurate evaluation of diagonal unitary operators is often the most resource-intensive element of quantum algorithms such as real-space quantum simulation and Grover search. Efficient circuits have been demonstrated in some cases but…

Quantum Physics · Physics 2015-06-16 Jonathan Welch , Daniel Greenbaum , Sarah Mostame , Alán Aspuru-Guzik

We propose a quantum algorithm for finding eigenvalues of non-unitary matrices. We show how to construct, through interactions in a quantum system and projective measurements, a non-Hermitian or non-unitary matrix and obtain its eigenvalues…

Quantum Physics · Physics 2010-12-07 Hefeng Wang , Lian-Ao Wu , Yu-xi Liu , Franco Nori

Unknown unitary inversion is a fundamental primitive in quantum computing and physics. Although recent work has demonstrated that quantum algorithms can invert arbitrary unknown unitaries without accessing their classical descriptions,…

Quantum Physics · Physics 2025-06-26 Yin Mo , Tengxiang Lin , Xin Wang

We report on recent developments in the integration of optical microresonators into atom chips and describe some fabrication and implementation challenges. We also review theoretical proposals for quantum computing with single atoms based…

Quantum Physics · Physics 2009-11-13 M. Trupke , J. Metz , A. Beige , E. A. Hinds

We propose quantum algorithms, purely quantum in nature, for calculating the determinant and inverse of an $(N-1)\times (N-1)$ matrix (depth is $O(N^2\log N)$) which is a simple modification of the algorithm for calculating the determinant…

Quantum Physics · Physics 2025-06-02 Alexander I. Zenchuk , Georgii A. Bochkin , Wentao Qi , Asutosh Kumar , Junde Wu

In the study of open quantum systems, one typically obtains the decoherence dynamics by solving a master equation. The master equation is derived using knowledge of some basic properties of the system, the environment and their interaction:…

Quantum Physics · Physics 2011-06-22 Hefeng Wang , S. Ashhab , Franco Nori

Estimating the eigenstate properties of quantum systems is a long-standing, challenging problem for both classical and quantum computing. Existing universal quantum algorithms typically rely on ideal and efficient query models (e.g. time…

Quantum Physics · Physics 2026-01-21 Jinzhao Sun , Pei Zeng , Tom Gur , M. S. Kim

We present a framework for computing the solution to Hamiltonian eigenproblems in a subspace defined by bit-strings sampled from a quantum computer. Hamiltonians are represented using an extended alphabet that includes projection and ladder…

Quantum Physics · Physics 2026-04-01 Paul D. Nation , Abdullah Ash Saki , Hwajung Kang

Nonlinear spectroscopy is a cornerstone of quantum science, providing unique access to multi-point correlations, quantum coherence, and couplings that are invisible to linear methods. However, classical simulation of these phenomena is…

Quantum Physics · Physics 2026-04-20 Long Xiong , Xiaoyang Wang , Xiaoxia Cai , Xiao Yuan

The characterization of observables, expressed via Hermitian operators, is a crucial task in quantum mechanics. For this reason, an eigensolver is a fundamental algorithm for any quantum technology. In this work, we implement a…

Quantum Physics · Physics 2021-06-15 C. -Y. Pan , M. Hao , N. Barraza , E. Solano , F. Albarran-Arriagada

We develop three new methods to implement any Linear Combination of Unitaries (LCU), a powerful quantum algorithmic tool with diverse applications. While the standard LCU procedure requires several ancilla qubits and sophisticated…

Quantum Physics · Physics 2024-10-16 Shantanav Chakraborty

We propose a practical, scalable, and efficient scheme for quantum computation using spatially separated matter qubits and single photon interference effects. The qubit systems can be NV-centers in diamond, Pauli-blockade quantum dots with…

Quantum Physics · Physics 2009-11-10 Sean D. Barrett , Pieter Kok

Quantum phase estimation is the workhorse behind any quantum algorithm and a promising method for determining ground state energies of strongly correlated quantum systems. Low-cost quantum phase estimation techniques make use of circuits…

Quantum Physics · Physics 2019-03-27 T. E. O'Brien , B. Tarasinski , B. M. Terhal

This paper summarizes a quantum algorithm of [R.D. Somma, et.al., Phys. Rev. Lett. 101, 130504 (2008)] that simulates a classical annealing process for solving discrete optimization problems. The complexity of the quantum algorithm scales…

Quantum Physics · Physics 2015-12-16 Sergio Boixo , Rolando D. Somma

We propose a circuit-model quantum algorithm for eigenpath traversal that is based on a combination of concepts from Grover's search and adiabatic quantum computation. Our algorithm deploys a sequence of reflections determined from…

Quantum Physics · Physics 2021-11-11 Jessica Lemieux , Artur Scherer , Pooya Ronagh

Quantum computing hardware has grown sufficiently complex that it often can no longer be simulated by classical computers, but its computational power remains limited by errors. These errors corrupt the results of quantum algorithms, and it…

We propose a quantum algorithm that emulates the action of an unknown unitary transformation on a given input state, using multiple copies of some unknown sample input states of the unitary and their corresponding output states. The…

Quantum Physics · Physics 2024-03-27 Iman Marvian , Seth Lloyd