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We propose a hybrid quantum-classical algorithm to compute approximate solutions of binary combinatorial problems. We employ a shallow-depth quantum circuit to implement a unitary and Hermitian operator that block-encodes the weighted…

Quantum Physics · Physics 2023-06-16 Natacha Kuete Meli , Florian Mannel , Jan Lellmann

Existing quantum compilers optimize quantum circuits by applying circuit transformations designed by experts. This approach requires significant manual effort to design and implement circuit transformations for different quantum devices,…

Programming Languages · Computer Science 2022-05-03 Mingkuan Xu , Zikun Li , Oded Padon , Sina Lin , Jessica Pointing , Auguste Hirth , Henry Ma , Jens Palsberg , Alex Aiken , Umut A. Acar , Zhihao Jia

In this study, we propose a new method for constrained combinatorial optimization using variational quantum circuits. Quantum computers are considered to have the potential to solve large combinatorial optimization problems faster than…

Quantum Physics · Physics 2025-07-15 Hyakka Nakada , Kotaro Tanahashi , Shu Tanaka

Quantum mechanics requires the operation of quantum computers to be unitary, and thus makes it important to have general techniques for developing fast quantum algorithms for computing unitary transforms. A quantum routine for computing a…

Quantum Physics · Physics 2007-05-23 Peter Hoyer

We investigate the classical communication over quantum channels when assisted by no-signaling (NS) and positive-partial-transpose-preserving (PPT) codes, for which both the optimal success probability of a given transmission rate and the…

Quantum Physics · Physics 2018-07-16 Xin Wang , Wei Xie , Runyao Duan

We show that an n-th root of the Walsh-Hadamard transform (obtained from the Hadamard gate and a cyclic permutation of the qubits), together with two diagonal matrices, namely a local qubit-flip (for a fixed but arbitrary qubit) and a…

Quantum Physics · Physics 2007-05-23 Simone Severini

Deutsch's algorithm is the first quantum algorithm to show the advantage over the classical algorithm. Here we generalize Deutsch's problem to $n$ functions and propose a new quantum algorithm with indefinite causal order to solve this…

Universal gate sets for quantum computing have been known for decades, yet no universal gate set has been proposed for particle-conserving unitaries, which are the operations of interest in quantum chemistry. In this work, we show that…

The quantum circuit model is the most commonly used model for implementing quantum computers and quantum neural networks whose essential tasks are to realize certain unitary operations. Here we propose an alternative approach; we use a…

Quantum Physics · Physics 2023-04-14 Jia-Yi Lin , Xin-Yu Li , Yu-Hao Shao , Wei Wang , Shengjun Wu

Quantum computing is a hotspot technology for its potential to accelerate specific applications by exploiting quantum parallelism. However, current physical quantum computers are limited to a relatively small scale, simulators based on…

Quantum Physics · Physics 2022-11-15 Jingcheng Shen , Linbo Long , Masao Okita , Fumihiko Ino

One-way measurement based quantum computations (1WQC) may describe unitary transformations, via a composition of CPTP maps which are not all unitary themselves. This motivates the following decision problems: Is it possible to determine…

Quantum Physics · Physics 2009-10-22 Niel de Beaudrap

We use a random search technique to find quantum gate sequences that implement perfect quantum state preparation or unitary operator synthesis with arbitrary targets. This approach is based on the recent discovery that there is a large…

Quantum Physics · Physics 2024-10-25 Sahel Ashhab , Fumiki Yoshihara , Miwako Tsuji , Mitsuhisa Sato , Kouichi Semba

We consider the general problem of the optimal transformation of N uses of (possibly different) unitary channels to a single use of another unitary channel in any finite dimension. We show how the optimal transformation can be fully…

Quantum Physics · Physics 2014-09-09 Alessandro Bisio , Giacomo Mauro D'Ariano , Paolo Perinotti , Michal Sedlak

In this work, we present two new methods for Variational Quantum Circuit (VQC) Process Tomography onto $n$ qubits systems: PT_VQC and U-VQSVD. Compared to the state of the art, PT_VQC halves in each run the required amount of qubits for…

Quantum Physics · Physics 2024-07-12 Vladlen Galetsky , Pol Julià Farré , Soham Ghosh , Christian Deppe , Roberto Ferrara

We study equivalence determination of unitary operations, a task analogous to quantum state discrimination. The candidate states are replaced by unitary operations given as a quantum sample, i.e., a black-box device implementing a candidate…

Quantum Physics · Physics 2018-04-02 Atsushi Shimbo , Akihito Soeda , Mio Murao

Here we show how universal quantum computers based on the quantum circuit model can handle mathematical analysis calculations for functions with continuous domains, without any digitalization, and with remarkably few qubits. The basic…

Quantum Physics · Physics 2022-10-10 Pablo Bermejo , Roman Orus

The simulation of quantum dynamics on a digital quantum computer with parameterized circuits has widespread applications in fundamental and applied physics and chemistry. In this context, using the hybrid quantum-classical algorithm,…

Quantum Physics · Physics 2023-07-19 Tangyou Huang , Yongcheng Ding , Léonce Dupays , Yue Ban , Man-Hong Yung , Adolfo del Campo , Xi Chen

In the problem of quantum channel certification, we have black box access to a quantum process and would like to decide if this process matches some predefined specification or is $\varepsilon$-far from this specification. The objective is…

Quantum Physics · Physics 2024-11-15 Omar Fawzi , Nicolas Flammarion , Aurélien Garivier , Aadil Oufkir

Random quantum circuits continue to inspire a wide range of applications in quantum information science and many-body quantum physics, while remaining analytically tractable through probabilistic methods. Motivated by an interest in…

Quantum Physics · Physics 2023-08-02 Grace M. Sommers , David A. Huse , Michael J. Gullans

Pseudo-unitary circuits are recurring in both S-matrix theory and analysis of No-Go theorems. We propose a matrix and diagrammatic representation for the operation that maps S-matrices to T-matrices and, consequently, a unitary group to a…

High Energy Physics - Theory · Physics 2025-12-04 Dennis Lima , Saif Al-Kuwari