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There is a clear need for efficient algorithms to tune hyperparameters for statistical learning schemes, since the commonly applied search methods (such as grid search with N-fold cross-validation) are inefficient and/or approximate.…

Machine Learning · Computer Science 2020-04-07 Luis Miguel Lopez-Ramos , Baltasar Beferull-Lozano

We propose a tomographic protocol for estimating any $ k $-body reduced density matrix ($ k $-RDM) of an $ n $-mode fermionic state, a ubiquitous step in near-term quantum algorithms for simulating many-body physics, chemistry, and…

Quantum Physics · Physics 2022-10-04 Andrew Zhao , Nicholas C. Rubin , Akimasa Miyake

Gate model quantum computers with too many qubits to be simulated by available classical computers are about to arrive. We present a strategy for programming these devices without error correction or compilation. This means that the number…

Quantum Physics · Physics 2017-03-21 E. Farhi , J. Goldstone , S. Gutmann , H. Neven

A new approach to efficient quantum computation with probabilistic gates is proposed and analyzed in both a local and non-local setting. It combines heralded gates previously studied for atom or atom-like qubits with logical encoding from…

Quantum Physics · Physics 2017-04-19 Johannes Borregaard , Anders S. Sørensen , Ignacio Cirac , Mikhail D. Lukin

In this paper, we propose a quantum algorithm that supports a real-valued higher-order unconstrained binary optimization (HUBO) problem. This algorithm is based on the Grover adaptive search that originally supported HUBO with integer…

Signal Processing · Electrical Eng. & Systems 2023-02-17 Masaya Norimoto , Ryuhei Mori , Naoki Ishikawa

We describe a simple algorithm for sampling $n$-qubit Clifford operators uniformly at random. The algorithm outputs the Clifford operators in the form of quantum circuits with at most $5n + 2n^2$ elementary gates and a maximum depth of…

Quantum Physics · Physics 2021-08-18 Ewout van den Berg

We design optimal interferometric schemes for implementation of two-qubit linear optical quantum filters diagonal in the computational basis. The filtering is realized by interference of the two photons encoding the qubits in a multiport…

Quantum Physics · Physics 2021-06-16 Jaromír Fiurášek , Robert Stárek , Michal Mičuda

We present an extension of the Evolving density matrices on Qubits (E$\rho$OQ) framework that enables efficient fault-tolerant preparation of fermionic quantum states. The original method circumvents state preparation by stochastic…

Quantum Physics · Physics 2026-03-25 Erik J. Gustafson , Henry Lamm

Recent reports of large photonic nonlinearities in integrated photonic devices, using the strong excitonic light-matter coupling in semiconductors, necessitate a tailored design framework for quantum processing in the limit of low photon…

Quantum Physics · Physics 2026-05-14 Mathias Van Regemortel , Thomas Van Vaerenbergh

Ultracold neutral atoms in optical lattices are a promising platform for simulating the behavior of complex materials and implementing quantum gates. We optimize collision gates for fermionic Lithium atoms confined in a double-well…

Quantum Gases · Physics 2026-04-10 Jan A. P. Reuter , Juhi Singh , Tommaso Calarco , Felix Motzoi , Robert Zeier

We experimentally demonstrate a single-qubit decohering quantum channel using linear optics. We implement the channel, whose special cases include both the amplitude-damping channel and the bit-flip channel, using a single, static optical…

Quantum Physics · Physics 2012-03-20 Kent Fisher , Robert Prevedel , Rainer Kaltenbaek , Kevin J. Resch

We prove the existence of barren plateaus in variational quantum algorithms using linear optics with either bosonic or fermionic particles and demonstrate that fermionic linear optics is less susceptible to the barren plateau problem. We…

Quantum Physics · Physics 2026-04-21 Matthew D. Horner

We prove that a classical computer can efficiently sample from the photon-number probability distribution of a Gaussian state prepared by using an optical circuit that is shallow and local. Our work generalizes previous known results for…

The Quantum Approximate Optimization Algorithm can naturally be applied to combinatorial search problems on graphs. The quantum circuit has p applications of a unitary operator that respects the locality of the graph. On a graph with…

Quantum Physics · Physics 2020-04-21 Edward Farhi , David Gamarnik , Sam Gutmann

We present new optimal and heuristic algorithms for exact synthesis of multi-qubit unitaries and isometries. For example, our algorithms find Clifford and T circuits for unitaries with entries in $\mathbb{Z}[i,1/\sqrt{2}]$. The optimal…

Quantum Physics · Physics 2024-05-30 Vadym Kliuchnikov , Sebastian Schönnenbeck

We show how techniques from machine learning and optimization can be used to find circuits of photonic quantum computers that perform a desired transformation between input and output states. In the simplest case of a single input state,…

We present a global optimization approach to optical flow estimation. The approach optimizes a classical optical flow objective over the full space of mappings between discrete grids. No descriptor matching is used. The highly regular…

Computer Vision and Pattern Recognition · Computer Science 2016-04-13 Qifeng Chen , Vladlen Koltun

The solving of linear systems provides a rich area to investigate the use of nearer-term, noisy, intermediate-scale quantum computers. In this work, we discuss hybrid quantum-classical algorithms for skewed linear systems for…

Quantum Physics · Physics 2021-04-28 Bujiao Wu , Maharshi Ray , Liming Zhao , Xiaoming Sun , Patrick Rebentrost

Fermionic ansatz state preparation is a critical subroutine in many quantum algorithms such as Variational Quantum Eigensolver for quantum chemistry and condensed matter applications. The shallowest circuit depth needed to prepare Slater…

Quantum Physics · Physics 2023-08-22 Chong Hian Chee , Daniel Leykam , Adrian M. Mak , Dimitris G. Angelakis

Quantum approximate optimization algorithm (QAOA) aims to solve discrete optimization problems by sampling bitstrings using a parameterized quantum circuit. The circuit parameters (angles) are optimized in the way that minimizes the cost…

Quantum Physics · Physics 2023-11-29 A. Yu. Chernyavskiy , B. I. Bantysh , Yu. I. Bogdanov