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Realizing non-unitary transformations on unitary-gate based quantum devices is critically important for simulating a variety of physical problems including open quantum systems and subnormalized quantum states. We present a dilation based…

We present verification protocols to gain confidence in the correct performance of the realization of an arbitrary universal quantum computation. The derivation of the protocols is based on the fact that matchgate computations, which are…

Quantum Physics · Physics 2025-08-11 Jose Carrasco , Marc Langer , Antoine Neven , Barbara Kraus

Reversing unitary operations is a key task in quantum computing and quantum control. In this work, we introduce and develop the framework of shadow unitary inversion, a relaxed variant of unitary inversion in which the goal is to reproduce…

Quantum Physics · Physics 2026-05-29 Guocheng Zhen , Yu-Ao Chen , Mingrui Jing , Jingu Xie , Ranyiliu Chen , Xin Wang

We propose a method of compiling that permits to identify quantum circuits able to simulate arbitrary $n$-qubit unitary operations via the adjustment of angles in single-qubit gates therein. The method of compiling itself extends older…

Quantum Physics · Physics 2021-01-06 Rahul P. Singh , A. Mandilara

We address the problem of learning an unknown unitary transformation from a finite number of examples. The problem consists in finding the learning machine that optimally emulates the examples, thus reproducing the unknown unitary maximum…

Quantum Physics · Physics 2010-07-01 A. Bisio , G. Chiribella , G. M. D'Ariano , S. Facchini , P. Perinotti

In the study of quantum computation, data is represented in terms of linear operators which form a generalized model of probability, and computations are most commonly described as products of unitary transformations, which are the…

Quantum Physics · Physics 2008-12-16 Jonathan Robert Niel de Beaudrap

Superconducting quantum circuit is a promising system for building quantum computer. With this system we demonstrate the universal quantum computations, including the preparing of initial states, the single-qubit operations, the two-qubit…

Quantum Physics · Physics 2018-09-06 Nian-Quan Jiang , Yao Chen , Chuanbing Cai , Ming-FengWang , Junwang Tang

An arbitrary lossless transformation in high-dimensional quantum space can be decomposed into elementary operations which are easy to implement, and an effective decomposition algorithm is important for constructing high-dimensional…

Quantum Physics · Physics 2022-12-07 Dong-Xu Chen , Junliang Jia , Pei Zhang , Chui-Ping Yang

From a geometric approach, we derive the minimum number of applications needed for an arbitrary Controlled-Unitary gate to construct a universal quantum circuit. A new analytic construction procedure is presented and shown to be either…

Quantum Physics · Physics 2009-11-10 Jun Zhang , Jiri Vala , Shankar Sastry , K. Birgitta Whaley

Optimization of circuits is an essential task for both quantum and classical computers to improve their efficiency. In contrast, classical logic optimization is known to be difficult, and a lot of heuristic approaches have been developed so…

Quantum Physics · Physics 2025-05-14 Yusei Mori , Hideaki Hakoshima , Kyohei Sudo , Toshio Mori , Kosuke Mitarai , Keisuke Fujii

We consider a unitary transformation which maps any given state of an $n$-qubit quantum register into another one. This transformation has applications in the initialization of a quantum computer, and also in some quantum algorithms.…

Quantum Physics · Physics 2007-05-23 Mikko Mottonen , Juha J. Vartiainen , Ville Bergholm , Martti M. Salomaa

The process of translating a quantum algorithm into a form suitable for implementation on a quantum computing platform is crucial but yet challenging. This entails specifying quantum operations with precision, a typically intricate task. In…

Quantum Physics · Physics 2024-08-26 M. Zomorodi , H. Amini , M. Abbaszadeh , J. Sohrabi , V. Salari , P. Plawiak

We demonstrate how insights gained from reformulating the problem of quantum teleportation into one of reversing quantum operations, and designing optimum completely positive maps for teleportation, can enable one to explore optimal…

Quantum Physics · Physics 2007-05-23 Ye Yeo

Quantum variational circuits have gained significant attention due to their applications in the quantum approximate optimization algorithm and quantum machine learning research. This work introduces a novel class of classical probabilistic…

Quantum Physics · Physics 2025-09-17 Gal Weitz , Lirandë Pira , Chris Ferrie , Joshua Combes

Unitary transformations are routinely modeled and implemented in the field of quantum optics. In contrast, nonunitary transformations that can involve loss and gain require a different approach. In this theory work, we present a universal…

Quantum Physics · Physics 2018-04-17 Nora Tischler , Carsten Rockstuhl , Karolina Słowik

Quantum combs play a vital role in characterizing and transforming quantum processes, with wide-ranging applications in quantum information processing. However, obtaining the explicit quantum circuit for the desired quantum comb remains a…

Quantum Physics · Physics 2025-02-26 Yin Mo , Lei Zhang , Yu-Ao Chen , Yingjian Liu , Tengxiang Lin , Xin Wang

Unitary designs are unitary ensembles that emulate Haar-random unitary statistics. They provide a vital tool for studying quantum randomness and have found broad applications in quantum technologies. However, existing research has focused…

Quantum Physics · Physics 2026-01-06 Xiaodong Yang , Jiaqing Leng , Jun Li

We present a protocol for transferring arbitrary continuous-variable quantum states into a few discrete-variable qubits and back. The protocol is deterministic and utilizes only two-mode Rabi-type interactions which are readily available in…

Quantum Physics · Physics 2022-04-06 Jacob Hastrup , Kimin Park , Jonatan Bohr Brask , Radim Filip , Ulrik Lund Andersen

In this research, we present a quantum circuit design and implementation for a parallel universal linear bounded automata. This circuit is able to accelerate the inference of algorithmic structures in data for discovering causal generative…

Quantum Physics · Physics 2022-02-25 Aritra Sarkar , Zaid Al-Ars , Koen Bertels

We give quantum circuits that simulate an arbitrary two-qubit unitary operator up to global phase. For several quantum gate libraries we prove that gate counts are optimal in worst and average cases. Our lower and upper bounds compare…

Quantum Physics · Physics 2013-05-29 Vivek V. Shende , Igor L. Markov , Stephen S. Bullock