Quantum

Paper

Connectivity constrains quantum codes

Nouédyn Baspin and Anirudh Krishna,

Quantum 6, 711 (2022).

Quantum low-density parity-check (LDPC) codes are an important class of quantum error correcting codes. In such codes, each qubit only affects a constant number of syndrome bits, and each sy…

Paper

Approaching the theoretical limit in quantum gate decomposition

Péter Rakyta and Zoltán Zimborás,

Quantum 6, 710 (2022).

In this work we propose a novel numerical approach to decompose general quantum programs in terms of single- and two-qubit quantum gates with a $CNOT$ gate count very close to the current theo…

Paper

Jet: Fast quantum circuit simulations with parallel task-based tensor-network contraction

Trevor Vincent, Lee J. O’Riordan, Mikhail Andrenkov, Jack Brown, Nathan Killoran, Haoyu Qi, and Ish Dhand,

Quantum 6, 709 (2022).

We introduce a new open-source software library $Jet$, which uses task-based parallelism to obtain speed-ups in classical tensor-network simulations of quantum circuits. These speed-ups result…

Paper

Finite-Function-Encoding Quantum States

Paul Appel, Alexander J. Heilman, Ezekiel W. Wertz, David W. Lyons, Marcus Huber, Matej Pivoluska, and Giuseppe Vitagliano,

Quantum 6, 708 (2022).

We introduce finite-function-encoding (FFE) states which encode arbitrary $d$-valued logic functions, i.e., multivariate functions over the ring of integers modulo $d$, and investigate some of t…

Paper

Re-examining the quantum volume test: Ideal distributions, compiler optimizations, confidence intervals, and scalable resource estimations

Charles H. Baldwin, Karl Mayer, Natalie C. Brown, Ciarán Ryan-Anderson, and David Hayes,

Quantum 6, 707 (2022).

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…

Paper

Fast simulation of quantum algorithms using circuit optimization

Gian Giacomo Guerreschi,

Quantum 6, 706 (2022).

Classical simulators play a major role in the development and benchmark of quantum algorithms and practically any software framework for quantum computation provides the option of running th…

Paper

Bending the rules of low-temperature thermometry with periodic driving

Jonas Glatthard and Luis A. Correa,

Quantum 6, 705 (2022).

There exist severe limitations on the accuracy of low-temperature thermometry, which poses a major challenge for future quantum-technological applications. Low-temperature sensitivity might…

Paper

Maximal entanglement increase with single-photon subtraction

Kun Zhang, Jietai Jing, Nicolas Treps, and Mattia Walschaers,

Quantum 6, 704 (2022).

Entanglement is an indispensable quantum resource for quantum information technology. In continuous-variable quantum optics, photon subtraction can increase the entanglement between Gaussian…

Paper

Unitary Selective Coupled-Cluster Method

Dmitry A. Fedorov, Yuri Alexeev, Stephen K. Gray, and Matthew Otten,

Quantum 6, 703 (2022).

Simulating molecules using the Variational Quantum Eigensolver method is one of the promising applications for NISQ-era quantum computers. Designing an efficient ansatz to represent the elec…

Paper

Entanglement Spectroscopy and probing the Li-Haldane Conjecture in Topological Quantum Matter

Torsten V. Zache, Christian Kokail, Bhuvanesh Sundar, and Peter Zoller,

Quantum 6, 702 (2022).

Topological phases are characterized by their entanglement properties, which is manifest in a direct relation between entanglement spectra and edge states discovered by Li and Haldane. We pr…

Paper

Eigenstate entanglement in integrable collective spin models

Meenu Kumari and Álvaro M. Alhambra,

Quantum 6, 701 (2022).

The average entanglement entropy (EE) of the energy eigenstates in non-vanishing partitions has been recently proposed as a diagnostic of integrability in quantum many-body systems. For it t…

Paper

Understanding and Improving Critical Metrology. Quenching Superradiant Light-Matter Systems Beyond the Critical Point

Karol Gietka, Lewis Ruks, and Thomas Busch,

Quantum 6, 700 (2022).

We carefully examine critical metrology and present an improved critical quantum metrology protocol which relies on quenching a system exhibiting a superradiant quantum phase transition beyo…

Paper

An Operational Environment for Quantum Self-Testing

Matthias Christandl, Nicholas Gauguin Houghton-Larsen, and Laura Mancinska,

Quantum 6, 699 (2022).

Observed quantum correlations are known to determine in certain cases the underlying quantum state and measurements. This phenomenon is known as $\textit{(quantum) self-testing}$. Self-testing…

Paper

The XYZ$^2$ hexagonal stabilizer code

Basudha Srivastava, Anton Frisk Kockum, and Mats Granath,

Quantum 6, 698 (2022).

We consider a topological stabilizer code on a honeycomb grid, the "XYZ$^2$" code. The code is inspired by the Kitaev honeycomb model and is a simple realization of a "matching code" discussed…

Paper

Back to sources – the role of losses and coherence in super-resolution imaging revisited

Stanislaw Kurdzialek,

Quantum 6, 697 (2022).

Photon losses are intrinsic for any translationally invariant optical imaging system with a non-trivial Point Spread Function, and the relation between the transmission factor and the cohere…

Paper

Optimal synthesis into fixed XX interactions

Eric C. Peterson, Lev S. Bishop, and Ali Javadi-Abhari,

Quantum 6, 696 (2022).

We describe an optimal procedure, as well as its efficient software implementation, for exact and approximate synthesis of two-qubit unitary operations into any prescribed discrete family of…

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