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This paper addresses the problem of designing universal quantum circuits to transform $k$ uses of a $d$-dimensional unitary input-operation into a unitary output-operation in a probabilistic heralded manner. Three classes of protocols are…

Quantum Physics · Physics 2020-04-16 Marco Túlio Quintino , Qingxiuxiong Dong , Atsushi Shimbo , Akihito Soeda , Mio Murao

In recent years, various frameworks have been proposed for the study of quantum processes with indefinite causal order. In particular, quantum circuits with quantum control of causal order (QC-QCs) form a broad class of physical supermaps…

Quantum Physics · Physics 2025-07-14 Maarten Grothus , Alastair A. Abbott , Augustin Vanrietvelde , Cyril Branciard

The concept of quantum phase transitions (QPT) plays a central role in the description of condensed matter systems. In this contribution, we perform high-quality wavefunction-based simulations to demonstrate the existence of a quantum phase…

Quantum Physics · Physics 2023-01-25 Tobias Serwatka , Roger G. Melko , Anton Burkov , Pierre-Nicholas Roy

In classical physics, events follow a definite causal order: the past influences the future, but not the reverse. Quantum theory, however, permits superpositions of causal orders -- so-called indefinite causal orders -- which can provide…

Quantum Physics · Physics 2026-04-29 Carla M. D. Richter , Michael Antesberger , Huan Cao , Philip Walther , Lee A. Rozema

Maximally entangled bipartite unitary operators or gates find various applications from quantum information to being building blocks of minimal models of many-body quantum chaos, and have been referred to as "dual unitaries". Dual unitary…

Quantum Physics · Physics 2020-08-19 Suhail Ahmad Rather , S. Aravinda , Arul Lakshminarayan

A major challenge in quantum communication is addressing the negative effects of noise on channel capacity, especially for completely depolarizing channels, where information transmission is inherently impossible. The concept of indefinite…

Quantum teleportation is a very helpful information-theoretic protocol that allows to transfer an unknown arbitrary quantum state from one location to another without having to transmit the quantum system through the intermediate region.…

Quantum Physics · Physics 2022-03-02 Marius Krumm , Philippe Allard Guérin , Thomas Zauner , Časlav Brukner

Quantum theory allows the traversing of multiple channels in a superposition of different orders. When the order in which the channels are traversed is controlled by an auxiliary quantum system, various unknown parameters of the channels…

Quantum Physics · Physics 2023-09-27 A. Z. Goldberg , L. L. Sanchez-Soto , K. Heshami

Since its discovery in the last century, quantum entanglement has challenged some of our most cherished classical views, such as locality and reality. Today, the second quantum revolution is in full swing and promises to revolutionize areas…

Quantum Physics · Physics 2020-07-15 Manuel Erhard , Mario Krenn , Anton Zeilinger

The aim of this thesis is to advance the theory behind quantum information processing tasks, by deriving fundamental limits on bipartite quantum interactions and dynamics, which corresponds to an underlying Hamiltonian that governs the…

Quantum Physics · Physics 2019-01-18 Siddhartha Das

Time crystals are nonequilibrium phases of matter characterized by the emergence of temporal ordering, in which an interacting many-body system develops robust structure in its time evolution that is not trivially dictated by the external…

Quantum Physics · Physics 2026-05-27 Gonzalo Camacho , Benedikt Fauseweh

We introduce the concept of quantum supermap, describing the most general transformation that maps an input quantum operation into an output quantum operation. Since quantum operations include as special cases quantum states, effects, and…

Quantum Physics · Physics 2008-10-22 G. Chiribella , G. M. D'Ariano , P. Perinotti

A two-dimensional quantum system with anyonic excitations can be considered as a quantum computer. Unitary transformations can be performed by moving the excitations around each other. Measurements can be performed by joining excitations in…

Quantum Physics · Physics 2009-10-30 A. Yu. Kitaev

Quantum networks play a major role in long-distance communication, quantum cryptography, clock synchronization, and distributed quantum computing. Generally, these protocols involve many independent sources sharing entanglement among…

Quantum Physics · Physics 2020-09-16 Johan Åberg , Ranieri Nery , Cristhiano Duarte , Rafael Chaves

We consider the quantum processor based on a chain of trapped ions to propose an architecture wherein the motional degrees of freedom of trapped ions (position and momentum) could be exploited as the computational Hilbert space. We adopt a…

Chaos transition, as an important topic, has become an active research subject in non-linear science. By considering a Dicke Hamiltonian coupled to a bath of harmonic oscillator, we have been able to introduce a logistic map with quantum…

Chaotic Dynamics · Physics 2012-07-25 S. Ahadpour , N. Hematpour

A major challenge to the control of infinite dimensional quantum systems is the irreversibility which is often present in the system dynamics. Here we consider systems with discrete-spectrum Hamiltonians operating over a Schwartz space…

Quantum Physics · Physics 2014-03-13 Roger S. Bliss , Daniel Burgarth

Quantum channels can describe all transformations allowed by quantum mechanics. We provide an explicit universal protocol to construct all possible quantum channels, using a single qubit ancilla with quantum non-demolition readout and…

The universal quantum computer is a device capable of simulating any physical system and represents a major goal for the field of quantum information science. Algorithms performed on such a device are predicted to offer significant gains…

Quantum Physics · Physics 2010-01-04 D. Hanneke , J. P. Home , J. D. Jost , J. M. Amini , D. Leibfried , D. J. Wineland

Randomness is both a useful way to model natural systems and a useful tool for engineered systems, e.g. in computation, communication and control. Fully random transformations require exponential time for either classical or quantum…

Quantum Physics · Physics 2016-05-04 Fernando G. S. L. Brandao , Aram W. Harrow , Michal Horodecki