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Recent work by Bravyi et al. constructs a relation problem that a noisy constant-depth quantum circuit (QNC$^0$) can solve with near certainty (probability $1 - o(1)$), but that any bounded fan-in constant-depth classical circuit (NC$^0$)…

Quantum Physics · Physics 2021-09-29 Daniel Grier , Nathan Ju , Luke Schaeffer

We present an efficient general method for realizing a quantum walk operator corresponding to an arbitrary sparse classical random walk. Our approach is based on Grover and Rudolph's method for preparing coherent versions of efficiently…

Quantum Physics · Physics 2013-06-12 Chen-Fu Chiang , Daniel Nagaj , Pawel Wocjan

We propose a general method to fully characterize a classical stochastic noise process causing qubit dephasing through repetitive Ramsey interferometry measurements (RIMs) on the qubit. Compared to filter-function-based spectroscopy, our…

Quantum Physics · Physics 2026-04-29 Yuan-De Jin , Zheng-Fei Ye , Wen-Long Ma

Many classical randomized algorithms (e.g., approximation algorithms for #P-complete problems) utilize the following random walk algorithm for {\em almost uniform sampling} from a state space $S$ of cardinality $N$: run a symmetric ergodic…

Quantum Physics · Physics 2007-05-23 Peter C. Richter

Quantum learning tasks often leverage randomly sampled quantum circuits to characterize unknown systems. An efficient approach known as "circuit reusing," where each circuit is executed multiple times, reduces the cost compared to…

Quantum Physics · Physics 2025-01-29 Zhuo Chen , Guoding Liu , Xiongfeng Ma

Classical Random Neural Networks (RNNs) have demonstrated effective applications in decision making, signal processing, and image recognition tasks. However, their implementation has been limited to deterministic digital systems that output…

Quantum Physics · Physics 2022-03-07 Debanjan Konar , Erol Gelenbe , Soham Bhandary , Aditya Das Sarma , Attila Cangi

A critical question for the field of quantum computing in the near future is whether quantum devices without error correction can perform a well-defined computational task beyond the capabilities of state-of-the-art classical computers,…

We consider quantum circuits consisting of randomly chosen two-local gates and study the number of gates needed for the distribution over measurement outcomes for typical circuit instances to be anti-concentrated, roughly meaning that the…

Quantum Physics · Physics 2022-03-08 Alexander M. Dalzell , Nicholas Hunter-Jones , Fernando G. S. L. Brandão

The computational complexity of simulating quantum many-body systems generally scales exponentially with the number of particles. This enormous computational cost prohibits first principles simulations of many important problems throughout…

Quantum Physics · Physics 2023-05-31 Chao Yin , Andrew Lucas

Understanding the computational power of noisy intermediate-scale quantum (NISQ) devices is of both fundamental and practical importance to quantum information science. Here, we address the question of whether error-uncorrected noisy…

Quantum Physics · Physics 2020-09-16 Kyungjoo Noh , Liang Jiang , Bill Fefferman

Recent technological developments have focused the interest of the quantum computing community on investigating how near-term devices could outperform classical computers for practical applications. A central question that remains open is…

Quantum Physics · Physics 2021-11-24 Daniel Stilck Franca , Raul Garcia-Patron

We construct a classical algorithm that designs quantum circuits for algorithmic quantum simulation of arbitrary qudit channels on fault-tolerant quantum computers within a pre-specified error tolerance with respect to diamond-norm…

Quantum Physics · Physics 2015-09-23 Dong-Sheng Wang , Barry C. Sanders

Quantum samplers are believed capable of sampling efficiently from distributions that are classically hard to sample from. We consider a sampler inspired by the classical Ising model. It is nonadaptive and therefore experimentally amenable.…

Quantum Physics · Physics 2019-07-17 Theodoros Kapourniotis , Animesh Datta

Simulating quantum circuits classically is an important area of research in quantum information, with applications in computational complexity and validation of quantum devices. One of the state-of-the-art simulators, that of Bravyi et al,…

Quantum Physics · Physics 2019-08-07 Hammam Qassim , Joel J. Wallman , Joseph Emerson

We consider estimation models of the form $Y=X^*+N$, where $X^*$ is some $m$-dimensional signal we wish to recover, and $N$ is symmetrically distributed noise that may be unbounded in all but a small $\alpha$ fraction of the entries. We…

Machine Learning · Computer Science 2022-11-15 Tommaso d'Orsi , Rajai Nasser , Gleb Novikov , David Steurer

Any technology requires precise benchmarking of its components, and the quantum technologies are no exception. Randomized benchmarking allows for the relatively resource economical estimation of the average gate fidelity of quantum gates…

Quantum Physics · Physics 2019-08-14 E. Onorati , A. H. Werner , J. Eisert

Simulating noisy quantum circuits is vital in designing and verifying quantum algorithms in the current NISQ (Noisy Intermediate-Scale Quantum) era, where quantum noise is unavoidable. However, it is much more inefficient than the classical…

Quantum Physics · Physics 2023-11-27 Mingyu Huang , Ji Guan , Wang Fang , Mingsheng Ying

Random quantum circuit sampling serves as a benchmark to demonstrate quantum computational advantage. Recent progress in classical algorithms, especially those based on tensor network methods, has significantly reduced the classical…

The current generation of quantum computing technologies call for quantum algorithms that require a limited number of qubits and quantum gates, and which are robust against errors. A suitable design approach are variational circuits where…

Quantum Physics · Physics 2020-04-10 Maria Schuld , Alex Bocharov , Krysta Svore , Nathan Wiebe

Simulating time evolution of generic quantum many-body systems using classical numerical approaches has an exponentially growing cost either with evolution time or with the system size. In this work, we present a polynomially scaling hybrid…

Quantum Physics · Physics 2023-09-18 Nikita Astrakhantsev , Sheng-Hsuan Lin , Frank Pollmann , Adam Smith