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There is a pressing need for more accurate computational simulations of the opto-electronic properties of defects in materials to aid in the development of quantum sensing platforms. In this work, we explore how quantum computers could be…

A new approach to dissipative quantum systems modelled by a system plus environment Hamiltonian is presented. Using a continuous sequence of infinitesimal unitary transformations the small quantum system is decoupled from its…

Statistical Mechanics · Physics 2009-10-30 Stefan Kehrein , Andreas Mielke

We introduce an alternative way to understand the decomposition of a quantum system into interacting parts and show that it is natural in several physical models. This enables us to define a reduced density operator for a working system…

Quantum Physics · Physics 2022-09-08 Adam Stokes

This paper is concerned with variational methods for nonlinear open quantum systems with Markovian dynamics governed by Hudson-Parthasarathy quantum stochastic differential equations. The latter are driven by quantum Wiener processes of the…

Quantum Physics · Physics 2016-11-17 Igor G. Vladimirov

Optimal control techniques are applied for the decomposition of unitary quantum operations into a sequence of single-qubit gates and entangling operations. To this end, we modify a gradient-ascent algorithm developed for systems of coupled…

Quantum Physics · Physics 2009-01-15 V. Nebendahl , H. Haffner , C. F. Roos

A system of linearly coupled quantum harmonic oscillators can be diagonalized when the system is dynamically stable using a Bogoliubov canonical transformation. However, this is just a particular case of more general canonical…

Quantum Physics · Physics 2019-03-14 Katja Kustura , Cosimo C. Rusconi , Oriol Romero-Isart

Accurate modeling of driven light-matter interactions is essential for quantum technologies, where natural and synthetic atoms are used to store and process quantum information, mediate interactions between bosonic modes, and enable…

Quantum Physics · Physics 2025-09-04 Martin Jirlow , Kunal Helambe , Axel M. Eriksson , Simone Gasparinetti , Tahereh Abad

We suggest and demonstrate a tomographic method to fully characterize homodyne detectors at the quantum level. The operator measure associated with the detector is expanded in the quadrature basis and probed with a set of coherent states.…

Quantum Physics · Physics 2024-02-15 Samuele Grandi , Alessandro Zavatta , Marco Bellini , Matteo G. A. Paris

Unknown unitary inversion is a fundamental primitive in quantum computing and physics. Although recent work has demonstrated that quantum algorithms can invert arbitrary unknown unitaries without accessing their classical descriptions,…

Quantum Physics · Physics 2025-06-26 Yin Mo , Tengxiang Lin , Xin Wang

We develop a non-adiabatic generalization of holonomic quantum computation in which high-speed universal quantum gates can be realized by using non-Abelian geometric phases. We show how a set of non-adiabatic holonomic one- and two-qubit…

Fault tolerant quantum simulation via the phase estimation algorithm and qubitization has a T-gate count that scales proportionally to the 1-norm of the Hamiltonian, the cost of block encoding the Hamiltonian, and inversely proportionally…

Quantum Physics · Physics 2025-04-14 Hirsh Kamakari , Emil Zak

Extending our previous work on time optimal quantum state evolution, we formulate a variational principle for the time optimal unitary operation, which has direct relevance to quantum computation. We demonstrate our method with three…

Quantum Physics · Physics 2014-12-01 Alberto Carlini , Akio Hosoya , Tatsuhiko Koike , Yosuke Okudaira

In this paper we discuss the utilization of Variational Quantum Solver (VQE) and recently introduced Generalized Unitary Coupled Cluster (GUCC) formalism for the diagonalization of downfolded/effective Hamiltonians in active spaces. In…

Quantum Physics · Physics 2020-11-05 Nicholas P. Bauman , Jaroslav Chládek , Libor Veis , Jiří Pittner , Karol Kowalski

Modeling composite systems of spins or electrons coupled to bosonic modes is of significant interest for many fields of applied quantum physics and chemistry. A quantum simulation can allow for the solution of quantum problems beyond…

Universal quantum computation using optical coherent states is studied. A teleportation scheme for a coherent-state qubit is developed and applied to gate operations. This scheme is shown to be robust to detection inefficiency.

Quantum Physics · Physics 2009-11-07 H. Jeong , M. S. Kim

For finite-dimensional quantum systems, such as qubits, a well established strategy to protect such systems from decoherence is dynamical decoupling. However many promising quantum devices, such as oscillators, are infinite dimensional, for…

Quantum Physics · Physics 2017-04-05 Christian Arenz , Robin Hillier , Daniel Burgarth

Gaussian quantum states of bosonic systems are an important class of states. In particular, they play a key role in quantum optics as all processes generated by Hamiltonians up to second order in the field operators (i.e. linear optics and…

Quantum Physics · Physics 2022-03-31 Jonatan Bohr Brask

Quantum operations by utilizing the underlying geometric phases produced in physical systems are favoured due to its potential robustness. When a system in a non-degenerate eigenstate undergoes an adiabatically cyclic evolution dominated by…

Quantum Physics · Physics 2024-05-22 Hao-Long Zhang , Yi-Hao Kang , Fan Wu , Zhen-Biao Yang , Shi-Biao Zheng

We study a linear array of coupled cavities interacting with two level systems and show how to construct individually addressable qubits in this system from the long-lived atom-photon excitations (polaritons) at each site. We derive the…

Quantum Physics · Physics 2009-11-13 Dimitris G. Angelakis , Alastair Kay

An adiabatic cyclic evolution of control parameters of a quantum system ends up with a holonomic operation on the system, determined entirely by the geometry in the parameter space. The operation is given either by a simple phase factor (a…

Quantum Physics · Physics 2014-01-23 Mahn-Soo Choi