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Designing multi-qubit quantum logic gates with experimental constraints is an important problem in quantum computing. Here, we develop a new quantum optimal control algorithm for finding unitary transformations with constraints on the…

Quantum Physics · Physics 2025-08-25 Dylan Lewis , Roeland Wiersema , Sougato Bose

In quantum adiabatic evolution algorithms, the quantum computer follows the ground state of a slowly varying Hamiltonian. The ground state of the initial Hamiltonian is easy to construct; the ground state of the final Hamiltonian encodes…

Quantum Physics · Physics 2007-05-23 Edward Farhi , Jeffrey Goldstone , Sam Gutmann

The geometric formulation of quantum mechanics is a very interesting field of research which has many applications in the emerging field of quantum computation and quantum information, such as schemes for optimal quantum computers. In this…

Quantum Physics · Physics 2014-04-24 Ole Andersson , Hoshang Heydari

Geometric quantum computation is the idea that geometric phases can be used to implement quantum gates, i.e., the basic elements of the Boolean network that forms a quantum computer. Although originally thought to be limited to adiabatic…

Quantum Physics · Physics 2016-09-16 Erik Sjöqvist , Vahid Azimi Mousolou , Carlo M. Canali

Recently, nonadiabatic geometric quantum computation has been received much attention, due to its fast manipulation and intrinsic error-resilience characteristics. However, to obtain universal geometric quantum control, only limited and…

Quantum Physics · Physics 2021-11-03 Cheng-Yun Ding , Yan Liang , Kai-Zhi Yu , Zheng-Yuan Xue

We study characteristics of quantum evolution which can be called curvature and torsion. The curvature shows a deviation of the state vector in quantum evolution from the geodesic line. The torsion shows a deviation of state vector from the…

Quantum Physics · Physics 2017-04-03 H. P. Laba , V. M. Tkachuk

From statistical distinguishability of probability distributions, one can define distinguishability of quantum states. A corresponding measurement to perform, optimal in a definite sense, for distinguishing between two given states rho_A…

Quantum Physics · Physics 2009-11-11 Asa Ericsson

We explore quantum search from the geometric viewpoint of a complex projective space $CP$, a space of rays. First, we show that the optimal quantum search can be geometrically identified with the shortest path along the geodesic joining a…

Quantum Physics · Physics 2009-11-07 Akimasa Miyake , Miki Wadati

Numerical computation of shortest paths or geodesics on curved domains, as well as the associated geodesic distance, arises in a broad range of applications across digital geometry processing, scientific computing, computer graphics, and…

Graphics · Computer Science 2020-07-22 Keenan Crane , Marco Livesu , Enrico Puppo , Yipeng Qin

This paper presents an introduction to geometric representations of quantum states in which each distinct quantum state, pure and mixed, corresponds to a unique point in a Euclidean space. Beginning with a review of some underappreciated…

Quantum Physics · Physics 2026-02-17 Athanasios Kostikas , Yaroslav Valchyshen , Paul Cadden-Zimansky

Nonadiabatic geometric phases are only dependent on the evolution path of a quantum system but independent of the evolution details, and therefore quantum computation based on nonadiabatic geometric phases is robust against control errors.…

Quantum Physics · Physics 2020-06-09 K. Z. Li , P. Z. Zhao , D. M. Tong

The speed of quantum evolution is limited under finite energy resources. While most quantum speed limits (QSLs) are formulated in terms of quantum states, they can be extended to the evolution operator itself, and thus impose fundamental…

Quantum Physics · Physics 2026-04-28 Hunter Nelson , Edwin Barnes

This work concerns a study of the quantum mechanical extension of the work of Horwitz et al. [1] on the stability of classical Hamiltonian systems by geometrical methods. Simulations are carried out for several important examples, these…

Quantum Physics · Physics 2017-04-12 Gil Elgressy , Lawrence Horwitz

We study the geodesics on the manifold of mixed quantum states for the Bures metric. It is shown that these geodesics correspond to physical non-Markovian evolutions of the system coupled to an ancilla. Furthermore, we argue that geodesics…

Quantum Physics · Physics 2025-04-23 Dominique Spehner

Geometric phases, arising from cyclic evolutions in a curved parameter space, appear in a wealth of physical settings. Recently, and largely motivated by the need of an experimentally realistic definition for quantum computing applications,…

Quantum Physics · Physics 2011-02-04 F. M. Cucchietti , J. -F. Zhang , F. C. Lombardo , P. I. Villar , R. Laflamme

As physical systems, qubits must evolve from input to output state. We describe a simple scheme in which the effect of a quantum gate is described by the action of an effective Hamiltonian acting for some characteristic time. This model…

Quantum Physics · Physics 2026-04-21 M. P. Vaughan

In this series of papers we aim to provide a mathematically comprehensive framework to the Hamiltonian pictures of quantum field theory in curved spacetimes. Our final goal is to study the kinematics and the dynamics of the theory from the…

We present a simple proof of the minimum time for the quantum evolution between two arbitrary states. This proof is performed in the absence of any geometrical arguments. Then, being in the geometric framework of quantum evolutions based…

Quantum Physics · Physics 2021-08-17 Carlo Cafaro , Paul M. Alsing

A monitored quantum system undergoing a cyclic evolution of the parameters governing its Hamiltonian accumulates a geometric phase that depends on the quantum trajectory followed by the system on its evolution. The phase value will be…

While most approaches to geometric quantum computation is based on geometric phase in cyclic evolution, noncyclic geometric gates have been proposed to increase further the flexibility. While these gates remove the dynamical phase of the…

Quantum Physics · Physics 2023-09-22 Nils Eivarsson , Erik Sjöqvist