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To employ a quantum device, the performance of the quantum gates in the device needs to be evaluated first. Since the dimensionality of a quantum gate grows exponentially with the number of qubits, evaluating the performance of a quantum…

Quantum Physics · Physics 2022-02-14 Maolin Luo , Xiaoqian Zhang , Xiaoqi Zhou

We introduce a single-number metric, quantum volume, that can be measured using a concrete protocol on near-term quantum computers of modest size ($n\lesssim 50$), and measure it on several state-of-the-art transmon devices, finding values…

Quantum Physics · Physics 2019-10-14 Andrew W. Cross , Lev S. Bishop , Sarah Sheldon , Paul D. Nation , Jay M. Gambetta

Future global quantum communication networks, or quantum Internet, will realize high-rate secure communication and entanglement distribution for large-scale users over long distances. Continuous variable (CV) quantum key distribution (QKD)…

Quantum Physics · Physics 2026-02-26 Zhiyue Zuo , Masoud Ghalaii , Stefano Pirandola

In this work we investigate how to quantify the coherence of quantum measurements. First, we establish a resource theoretical framework to address the coherence of measurement and show that any statistical distance can be adopted to define…

Quantum Physics · Physics 2020-08-11 Kyunghyun Baek , Adel Sohbi , Jaehak Lee , Jaewan Kim , Hyunchul Nha

High-dimensional entanglement has been identified as an important resource in quantum information processing, and also as a main obstacle for simulating quantum systems. Its certification is often difficult, and most widely used methods for…

Quantum Physics · Physics 2024-01-31 Shuheng Liu , Matteo Fadel , Qiongyi He , Marcus Huber , Giuseppe Vitagliano

We present two measures of distance between quantum processes based on the superfidelity, introduced recently to provide an upper bound for quantum fidelity. We show that the introduced measures partially fulfill the requirements for…

Quantum Physics · Physics 2011-01-26 Zbigniew Puchała , Jarosław Adam Miszczak , Piotr Gawron , Bartłomiej Gardas

The ability to transfer coherent quantum information between systems is a fundamental component of quantum technologies and leads to coherent correlations within the global quantum process. However correlation structures in quantum channels…

Quantum Physics · Physics 2022-05-03 Matthew Girling , Cristina Cirstoiu , David Jennings

Building scalable and secure quantum networks requires advanced quantum key distribution (QKD) protocols that support multi-user connectivity. Continuous-variable (CV) measurement-device-independent (MDI) QKD, which eliminates all detector…

Quantum Physics · Physics 2024-10-18 Adnan A. E. Hajomer , Ulrik L Andersen , Tobias Gehring

Present-day quantum devices require precise implementation of desired quantum channels. To characterize the quality of implementation one uses the average operation fidelity $F$, defined as the fidelity between an initial pure state and its…

Quantum Physics · Physics 2024-03-18 Igor Chełstowski , Grzegorz Rajchel-Mieldzioć , Karol Życzkowski

Efficient measures to determine similarity of quantum states, such as the fidelity metric, have been widely studied. In this paper, we address the problem of defining a similarity measure for quantum operations that can be…

Quantum Physics · Physics 2022-11-23 Yiyou Chen , Hideyuki Miyahara , Louis-S. Bouchard , Vwani Roychowdhury

We propose and investigate bounds on quantum process fidelity of quantum filters, i.e. probabilistic quantum operations represented by a single Kraus operator K. These bounds generalize the Hofmann bounds on quantum process fidelity of…

Quantum Physics · Physics 2016-08-08 Michal Sedlak , Jaromír Fiurášek

Estimating the fidelity between a desired target quantum state and an actual prepared state is essential for assessing the success of experiments. For pure target states, we use functional representations that can be measured directly and…

Quantum Physics · Physics 2024-09-09 Omar Fawzi , Aadil Oufkir , Robert Salzmann

We derive a general limit on the fidelity of a quantum channel conveying an ensemble of pure states. Unlike previous results, this limit applies to arbitrary coding and decoding schemes, including nonunitary decoding. This establishes the…

Quantum Physics · Physics 2016-09-08 Howard Barnum , Christopher A. Fuchs , Richard Jozsa , Benjamin Schumacher

Protocols for discriminating between a pair of channels or for estimating a channel parameter can often be aided by adaptivity or by entanglement between the probe states. This can make it difficult to bound the best possible performance…

Quantum Physics · Physics 2021-10-07 Jason L. Pereira , Leonardo Banchi , Stefano Pirandola

Entanglement fidelity quantifies how well a quantum channel preserves the correlations between a transmitted system and an inaccessible reference system. We derive closed-form expressions for the entanglement fidelity associated with…

Quantum Physics · Physics 2026-03-10 Niccolò Zanieri , Marios Kountouris

We present strictly efficient schemes for scalable measurement-based quantum computing using continuous-variable systems: These schemes are based on suitable non-Gaussian resource states, ones that can be prepared using interactions of…

Quantum Physics · Physics 2013-05-30 Matthias Ohliger , Jens Eisert

We consider quantum fidelity between two states $\rho$ and $\sigma$, where we fix $\rho$ and allow $\sigma$ to be sent through a quantum channel. We determine the minimal fidelity where one minimizes over (a) all unital channels, (b) all…

Quantum Physics · Physics 2015-09-11 Jin Li , Rajesh Pereira , Sarah Plosker

The quantum volume test is a full-system benchmark for quantum computers that is sensitive to qubit number, fidelity, connectivity, and other quantities believed to be important in building useful devices. The test was designed to produce a…

Quantum Physics · Physics 2022-05-11 Charles H. Baldwin , Karl Mayer , Natalie C. Brown , Ciarán Ryan-Anderson , David Hayes

Quantum benchmarks are routinely used to validate the experimental demonstration of quantum information protocols. Many relevant protocols, however, involve an infinite set of input states, of which only a finite subset can be used to test…

Quantum Physics · Physics 2021-09-28 Ge Bai , Giulio Chiribella

Motivated by the gate set tomography we study quantum channels from the perspective of information which is invariant with respect to the gauge realized through similarity of matrices representing channel superoperators. We thus use the…

Quantum Physics · Physics 2018-04-13 Łukasz Rudnicki , Zbigniew Puchała , Karol Zyczkowski