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We study bipartite unitary operators which stay invariant under the local actions of diagonal unitary and orthogonal groups. We investigate structural properties of these operators, arguing that the diagonal symmetry makes them suitable for…

Quantum Physics · Physics 2022-06-08 Satvik Singh , Ion Nechita

We show how to efficiently generate pseudo-random states suitable for quantum information processing via cluster-state quantum computation. By reformulating pseudo-random algorithms in the cluster-state picture, we identify a strategy for…

Quantum Physics · Physics 2009-11-13 Winton G. Brown , Yaakov S. Weinstein , Lorenza Viola

We consider pseudo-unitary quantum systems and discuss various properties of pseudo-unitary operators. In particular we prove a characterization theorem for block-diagonalizable pseudo-unitary operators with finite-dimensional diagonal…

Mathematical Physics · Physics 2015-06-26 Ali Mostafazadeh

Projective measurements of a single two-level quantum mechanical system (a qubit) evolving under a time-independent Hamiltonian produce a probability distribution that is periodic in the evolution time. The period of this distribution is an…

Quantum Physics · Physics 2012-06-05 Christopher Ferrie , Christopher E. Granade , D. G. Cory

Variational quantum algorithms are promising applications of noisy intermediate-scale quantum (NISQ) computers. These algorithms consist of a number of separate prepare-and-measure experiments that estimate terms in a Hamiltonian. The…

Quantum Physics · Physics 2020-06-25 Andrew Zhao , Andrew Tranter , William M. Kirby , Shu Fay Ung , Akimasa Miyake , Peter Love

Many applications of practical interest rely on time evolution of Hamiltonians that are given by a sum of Pauli operators. Quantum circuits for exact time evolution of single Pauli operators are well known, and can be extended trivially to…

Quantum Physics · Physics 2020-09-16 Ewout van den Berg , Kristan Temme

We present a general method for simulating an action of $t$ copies of a Haar random unitary for arbitrary compact groups. This construction can be viewed as a representation-theoretic generalization of Zhandry's compressed function oracle…

Quantum Physics · Physics 2025-10-01 Dmitry Grinko , Satoshi Yoshida

The linear combination of unitaries (LCU) method has proven to scale better than existing product formulas in simulating long time Hamiltonian dynamics. However, given the number of multi-control gate operations in the standard…

We introduce a new approach for the robust control of quantum dynamics of strongly interacting many-body systems. Our approach involves the design of periodic global control pulse sequences to engineer desired target Hamiltonians that are…

Quantum Physics · Physics 2020-07-08 Joonhee Choi , Hengyun Zhou , Helena S. Knowles , Renate Landig , Soonwon Choi , Mikhail D. Lukin

Randomness generation through quantum-chaotic evolution underpins foundational questions in statistical mechanics and applications across quantum information science, including benchmarking, tomography, metrology, and demonstrations of…

Statistical Mechanics · Physics 2026-01-01 Souradeep Ghosh , Nicholas Hunter-Jones , Joaquin F. Rodriguez-Nieva

We demonstrate how structured decompositions of unitary operators can be employed to derive control schemes for finite-level quantum systems that require only sequences of simple control pulses such as square wave pulses with finite rise…

Quantum Physics · Physics 2009-11-07 S. G. Schirmer , A. D. Greentree , V. Ramakrishna , H. Rabitz

We study a spin-1/2-particle moving on a one dimensional lattice subject to disorder induced by a random, space-dependent quantum coin. The discrete time evolution is given by a family of random unitary quantum walk operators, where the…

Quantum Physics · Physics 2015-05-27 Andre Ahlbrecht , Volkher B. Scholz , Albert H. Werner

We consider a bipartite quantum object, composed of a quantum system and a quantum actuator which is periodically reset. We show that the reduced dynamics of the system approaches unitarity as the reset frequency of the actuator is…

Quantum Physics · Physics 2016-04-05 David Layden , Eduardo Martin-Martinez , Achim Kempf

We explore how to build quantum circuits that compute the lowest energy state corresponding to a given Hamiltonian within a Symmetry subspace by explicitly encoding it into the circuit. We create an explicit unitary and a variationally…

Quantum Physics · Physics 2021-12-28 Raja Selvarajan , Manas Sajjan , Sabre Kais

Unitary t-designs are some of the most versatile tools in quantum information theory. Their applications range from randomized benchmarking and shadow tomography, to more fundamental ones such as emulating quantum chaos and establishing…

Quantum Physics · Physics 2026-03-04 Namit Anand , Jeffrey Marshall , Jason Saied , Eleanor Rieffel , Andrea Morello

Background. Designing trials to reduce treatment duration is important in several therapeutic areas, including TB and antibiotics. We recently proposed a new randomised trial design to overcome some of the limitations of standard two-arm…

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

We prove that random quantum circuits on any geometry, including a 1D line, can form approximate unitary designs over $n$ qubits in $\log n$ depth. In a similar manner, we construct pseudorandom unitaries (PRUs) in 1D circuits in…

Quantum Physics · Physics 2025-01-07 Thomas Schuster , Jonas Haferkamp , Hsin-Yuan Huang

Recently, a generalization of the standard optical multiport was proposed [Phys. Rev. A 93, 043845 (2016)]. These directionally unbiased multiports allow photons to reverse direction and exit backwards from the input port, providing a…

Quantum Physics · Physics 2017-04-12 David S. Simon , Casey A. Fitzpatrick , Shuto Osawa , Alexander V. Sergienko

Pseudo-random operators consist of sets of operators that exhibit many of the important statistical features of uniformly distributed random operators. Such pseudo-random sets of operators are most useful whey they may be parameterized and…

Quantum Physics · Physics 2009-11-10 Joseph Emerson