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We investigate the energy-constrained (EC) diamond norm distance between unitary channels acting on possibly infinite-dimensional quantum systems, and establish a number of results. Firstly, we prove that optimal EC discrimination between…

Quantum Physics · Physics 2021-05-14 Simon Becker , Nilanjana Datta , Ludovico Lami , Cambyse Rouzé

Scalable quantum networks rely on optical connections between long-lived qubits to distribute entanglement. Tin vacancies in diamond have emerged as promising long-lived qubits, offering extended spin coherence times at liquid helium…

We prove that a broad array of capacities of a quantum channel are continuous. That is, two channels that are close with respect to the diamond norm have correspondingly similar communication capabilities. We first show that the classical…

Quantum Physics · Physics 2009-09-09 Debbie Leung , Graeme Smith

We report the first successful application of the {\it ab initio} quantum Monte Carlo (QMC) framework to a phonon dispersion calculation. A full phonon dispersion of diamond is successfully calculated at the variational Monte Carlo (VMC)…

Materials Science · Physics 2021-04-14 Kousuke Nakano , Tommaso Morresi , Michele Casula , Ryo Maezono , Sandro Sorella

A programmable quantum processor is a fundamental model of quantum computation. In this model, any quantum channel can be approximated by applying a fixed universal quantum operation onto an input state and a quantum `program' state, whose…

Quantum Physics · Physics 2020-05-20 Leonardo Banchi , Jason Pereira , Seth Lloyd , Stefano Pirandola

We consider the family of energy-constrained diamond norms on the set of Hermitian-preserving linear maps (superoperators) between Banach spaces of trace class operators. We prove that any norm from this family generates the strong…

Quantum Physics · Physics 2018-05-15 M. E. Shirokov

In machine learning and particularly in topological data analysis, $\epsilon$-graphs are important tools but are generally hard to compute as the distance calculation between n points takes time O(n^2) classically. Recently, quantum…

Data Structures and Algorithms · Computer Science 2023-06-08 Naomi Mona Chmielewski , Nina Amini , Paulin Jacquot , Joseph Mikael

In this work, we consider the preservation of a measurement for quantum systems interacting with an environment. Namely, a method of preserving an optimal measurement over a channel is devised, what we call channel coding of a quantum…

Quantum Physics · Physics 2019-08-29 Spiros Kechrimparis , Chahan M. Kropf , Filip Wudarski , Joonwoo Bae

We introduce an algorithm that is able to find the facets of Coulomb diamonds in quantum dot arrays. We simulate these arrays using the constant-interaction model, and rely only on one-dimensional raster scans (rays) to learn a model of the…

Mesoscale and Nanoscale Physics · Physics 2022-10-19 Oswin Krause , Anasua Chatterjee , Ferdinand Kuemmeth , Evert van Nieuwenburg

We propose protocols for determining the distances in Hilbert space between pure and mixed quantum states prepared on a quantum computer. In the case of pure quantum states, the protocol is based on measuring the square of modulus of scalar…

Quantum Physics · Physics 2021-08-27 A. R. Kuzmak

Realizing robust quantum information transfer between long-lived qubit registers is a key challenge for quantum information science and technology. Here we demonstrate unconditional teleportation of arbitrary quantum states between diamond…

We show that the generalization of the relative entropy of a resource from states to channels is not unique, and there are at least six such generalizations. We then show that two of these generalizations are asymptotically continuous,…

Quantum Physics · Physics 2019-10-10 Gilad Gour , Andreas Winter

A method for channel estimation in wideband massive Multiple-Input Multiple-Output (MIMO) systems using covariance identification is developed. The method is useful for Frequency-Division Duplex (FDD) at either sub-6GHz or millimeter wave…

Signal Processing · Electrical Eng. & Systems 2024-10-30 José González-Coma , Pedro Suárez-Casal , Paula M. Castro , Luis Castedo , Michael Joham

A closed-form algorithm, named "concerto", is proposed for phase-based distance estimation in multi-frequency phase unwrapping (MFPU) system. The concerto method consists of three coherent estimation stages,i.e., initial modified BW…

Information Theory · Computer Science 2017-02-21 Li Wei , Wangdong Qi

In quantum information, trace distance is a basic metric of distinguishability between quantum states. However, there is no known efficient approach to estimate the value of trace distance in general. In this paper, we propose efficient…

Quantum Physics · Physics 2024-03-25 Qisheng Wang , Zhicheng Zhang

Crystal strain variation imposes significant limitations on many quantum sensing and information applications for solid-state defect qubits in diamond. Thus, precision measurement and control of diamond crystal strain is a key challenge.…

Large-scale quantum networks will enable entirely new applications of quantum information science in fields such as quantum communication, distributed quantum computing, sensing, and metrology. To build nodes of such networks, diamond color…

Quantum Physics · Physics 2026-05-29 Ayan Majumder , Cem Güney Torun , Tim Schröder , Gregor Pieplow , Prem Kumar , Kasturi Saha

We provide an overview of the experimental techniques, measurement modalities, and diverse applications of the Quantum Diamond Microscope (QDM). The QDM employs a dense layer of fluorescent nitrogen-vacancy (NV) color centers near the…

We present a technique to nanomechanically vary the distance between a fluorescent source and a mirror, thereby varying the local density of optical states at the source position. Our method can therefore serve to measure the quantum…

Optics · Physics 2015-06-12 Martin Frimmer , Abbas Mohtashami , A. Femius Koenderink

The recently introduced atomic norm minimization (ANM) framework for parameter estimation is a promising candidate towards low overhead channel estimation in wireless communications. However, previous works on ANM-based channel estimation…

Information Theory · Computer Science 2018-09-05 Stelios Stefanatos , Mahdi Barzegar Khalilsarai , Gerhard Wunder