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We show how to approximately represent a quantum state using the square root of the usual amount of classical memory. The classical representation of an $n$-qubit state $\psi$ consists of its inner products with $O(\sqrt{2^n})$ stabilizer…

Quantum Physics · Physics 2019-07-01 David Gosset , John Smolin

We present a covariant quantum formalism for scalar particles based on an enlarged Hilbert space. The particular physical theory can be introduced through a timeless Wheeler DeWitt-like equation, whose projection onto four-dimensional…

Quantum Physics · Physics 2020-01-08 N. L. Diaz , J. M. Matera , R. Rossignoli

The operator-sum decomposition (OS) of a mapping from one density matrix to another has many applications in quantum information science. To this mapping there corresponds an affine map which provides a geometric description of the density…

Quantum Physics · Physics 2011-02-10 Mark S. Byrd , C. Allen Bishop , Yong-Cheng Ou

We present quantum algorithms for the simulation of quantum systems in one spatial dimension, which result in quantum speedups that range from superpolynomial to polynomial. We first describe a method to simulate the evolution of the…

Quantum Physics · Physics 2016-08-09 Rolando D. Somma

Quantum algorithms profit from the interference of quantum states in an exponentially large Hilbert space and the fact that unitary transformations on that Hilbert space can be broken down to universal gates that act only on one or two…

Quantum Physics · Physics 2022-03-14 Daniel Braun , Ronny Müller

We study the time evolution of a PT-symmetric, non-Hermitian quantum system for which the associated phase space is compact. We focus on the simplest non-trivial example of such a Hamiltonian, which is linear in the angular momentum…

Quantum Physics · Physics 2021-08-18 Iván F. Valtierra , Mario Gaeta , Adrian Ortega , Thomas Gorin

We prove that there is no relaxation gap between a quasi-dissipative nonlinear evolution equation in a Hilbert space and its linear Liouville equation reformulation on probability measures. In other words, strong and generalized solutions…

Analysis of PDEs · Mathematics 2025-07-08 Saroj Prasad Chhatoi , Didier Henrion , Swann Marx , Nicolas Seguin

In this paper, we present quantum algorithms for a class of highly-oscillatory transport equations, which arise in semiclassical computation of surface hopping problems and other related non-adiabatic quantum dynamics, based on the…

Numerical Analysis · Mathematics 2025-09-05 Anjiao Gu , Shi Jin

We consider the relation between three different approaches to defining quantum states across several times and locations: the pseudo-density matrix (PDM), the process matrix, and the multiple-time state approaches. Previous studies have…

Quantum Physics · Physics 2024-03-14 Xiangjing Liu , Zhian Jia , Yixian Qiu , Fei Li , Oscar Dahlsten

We introduce a new density for the representation of quantum states on phase space. It is constructed as a weighted difference of two smooth probability densities using the Husimi function and first-order Hermite spectrograms. In contrast…

Mathematical Physics · Physics 2016-03-07 Johannes Keller , Caroline Lasser , Tomoki Ohsawa

Born proposed a unification of special relativity and quantum mechanics that placed position, time, energy and momentum on equal footing through a reciprocity principle and extended the usual position-time and energy-momentum line elements…

Mathematical Physics · Physics 2009-10-30 Stephen G. Low

Physical processes evolving in both time and space are often modeled using Partial Differential Equations (PDEs). Recently, it has been shown how stability analysis and control of coupled PDEs in a single spatial variable can be more…

Analysis of PDEs · Mathematics 2026-05-20 Declan S. Jagt , Matthew M. Peet

Eighth-BPS local operators in N=4 SYM are dual to quantum states arising from the quantization of a moduli space of giant gravitons in AdS5xS5. Earlier results on the quantization of this moduli space give a Hilbert space of multiple…

High Energy Physics - Theory · Physics 2015-06-03 Jurgis Pasukonis , Sanjaye Ramgoolam

We present an operational reconstruction of the well-known two-to-one homomorphism between the groups $SU(2)$ and $SO(3)$, grounded in the physical description of quantum state preparation and evolution. Starting from the connection between…

Quantum Physics · Physics 2025-12-02 V. G. Valle , B. F. Rizzuti

Quantum singular value transformation (QSVT) enables the application of polynomial functions to the singular values of near arbitrary linear operators embedded in unitary transforms, and has been used to unify, simplify, and improve most…

Quantum Physics · Physics 2023-04-28 Zane M. Rossi , Victor M. Bastidas , William J. Munro , Isaac L. Chuang

Quantum superposition says that any physical system simultaneously exists in all of its possible states, the number of which is exponential in the number of entities composing the system. The strength of presence of each possible state in…

Neural and Evolutionary Computing · Computer Science 2017-07-19 Gerard J. Rinkus

The exact and semiclassical quantum mechanics of the elliptic billiard is investigated. The classical system is integrable and exhibits a separatrix, dividing the phasespace into regions of oscillatory and rotational motion. The classical…

chao-dyn · Physics 2008-02-03 H. Waalkens , J. Wiersig , H. R. Dullin

Surface codes based on stabilizer circuits may pave the way for large scale fault-tolerant quantum computation. The surface code uses only single- and two-qubit gates and the error threshold falls close to 1% for a large range of errors.…

Quantum Physics · Physics 2019-08-28 H. W. L. Naus , R. Versluis

Quantum computers solve ever more complex tasks using steadily growing system sizes. Characterizing these quantum systems is vital, yet becoming increasingly challenging. The gold-standard is quantum state tomography (QST), capable of fully…

An adapted representation of quantum mechanics sheds new light on the relationship between quantum states and classical states. In this approach the space of quantum states splits into a product of the state space of classical mechanics and…

High Energy Physics - Theory · Physics 2021-04-14 Christoph Nölle