Quantum

Paper

General parameter-shift rules for quantum gradients

David Wierichs, Josh Izaac, Cody Wang, and Cedric Yen-Yu Lin,

Quantum 6, 677 (2022).

Variational quantum algorithms are ubiquitous in applications of noisy intermediate-scale quantum computers. Due to the structure of conventional parametrized quantum gates, the evaluated fu…

Paper

Representation of binary classification trees with binary features by quantum circuits

Raoul Heese, Patricia Bickert, and Astrid Elisa Niederle,

Quantum 6, 676 (2022).

We propose a quantum representation of binary classification trees with binary features based on a probabilistic approach. By using the quantum computer as a processor for probability distri…

Paper

Hybrid quantum-classical approach for coupled-cluster Green’s function theory

Trevor Keen, Bo Peng, Karol Kowalski, Pavel Lougovski, and Steven Johnston,

Quantum 6, 675 (2022).

The three key elements of a quantum simulation are state preparation, time evolution, and measurement. While the complexity scaling of time evolution and measurements are well known, many st…

Paper

Photon-photon interactions in Rydberg-atom arrays

Lida Zhang, Valentin Walther, Klaus Mølmer, and Thomas Pohl,

Quantum 6, 674 (2022).

We investigate the interaction of weak light fields with two-dimensional lattices of atoms with high lying atomic Rydberg states. This system features different interactions that act on disp…

Paper

Unlimited non-causal correlations and their relation to non-locality

Ämin Baumeler, Amin Shiraz Gilani, and Jibran Rashid,

Quantum 6, 673 (2022).

Non-causal correlations certify the lack of a definite causal order among localized space-time regions. In stark contrast to scenarios where a single region influences its own causal past, s…

Paper

Operational nonclassicality in minimal autonomous thermal machines

Jonatan Bohr Brask, Fabien Clivaz, Géraldine Haack, and Armin Tavakoli,

Quantum 6, 672 (2022).

Thermal machines exploit interactions with multiple heat baths to perform useful tasks, such as work production and refrigeration. In the quantum regime, tasks with no classical counterpart…

Paper

Local and scalable detection of genuine multipartite single-photon path entanglement

Patrik Caspar, Enky Oudot, Pavel Sekatski, Nicolas Maring, Anthony Martin, Nicolas Sangouard, Hugo Zbinden, and Rob Thew,

Quantum 6, 671 (2022).

How can a multipartite single-photon path-entangled state be certified efficiently by means of local measurements? We address this question by constructing an entanglement witness based on l…

Paper

Variational quantum amplitude estimation

Kirill Plekhanov, Matthias Rosenkranz, Mattia Fiorentini, and Michael Lubasch,

Quantum 6, 670 (2022).

We propose to perform amplitude estimation with the help of constant-depth quantum circuits that variationally approximate states during amplitude amplification. In the context of Monte Carl…

Paper

Proposal for room-temperature quantum repeaters with nitrogen-vacancy centers and optomechanics

Jia-Wei Ji, Yu-Feng Wu, Stephen C. Wein, Faezeh Kimiaee Asadi, Roohollah Ghobadi, and Christoph Simon,

Quantum 6, 669 (2022).

We propose a quantum repeater architecture that can operate under ambient conditions. Our proposal builds on recent progress towards non-cryogenic spin-photon interfaces based on nitrogen-va…

Paper

The Pursuit of Uniqueness: Extending Valiant-Vazirani Theorem to the Probabilistic and Quantum Settings

Dorit Aharonov, Michael Ben-Or, Fernando G.S.L. Brandão, and Or Sattath,

Quantum 6, 668 (2022).

Valiant-Vazirani showed in 1985 [45] that solving NP with the promise that "yes" instances have only one witness is powerful enough to solve the entire NP class (under randomized reductions)…

Paper

Optimizing quantum codes with an application to the loss channel with partial erasure information

Benjamin Desef and Martin B. Plenio,

Quantum 6, 667 (2022).

Quantum error correcting codes (QECCs) are the means of choice whenever quantum systems suffer errors, e.g., due to imperfect devices, environments, or faulty channels. By now, a plethora of…

Paper

Quantum scrambling of observable algebras

Paolo Zanardi,

Quantum 6, 666 (2022).

In this paper we describe an algebraic/geometrical approach to quantum scrambling. Generalized quantum subsystems are described by an hermitian-closed unital subalgebra $\cal A$ of operators e…

Paper

Imaginarity-free quantum multiparameter estimation

Jisho Miyazaki and Keiji Matsumoto,

Quantum 6, 665 (2022).

Multiparameter quantum estimation is made difficult by the following three obstacles. First, incompatibility among different physical quantities poses a limit on the attainable precision. Se…

Paper

Discrete-Time Quantum-Walk & Floquet Topological Insulators via Distance-Selective Rydberg-Interaction

Mohammadsadegh Khazali,

Quantum 6, 664 (2022).

This article proposes the first discrete-time implementation of Rydberg quantum walk in multi-dimensional spatial space that could ideally simulate different classes of topological insulator…

Paper

A no-go theorem for superpositions of causal orders

Fabio Costa,

Quantum 6, 663 (2022).

The causal order of events need not be fixed: whether a bus arrives before or after another at a certain stop can depend on other variables – like traffic. Coherent quantum control of causal…

Paper

On entanglement assistance to a noiseless classical channel

Péter E. Frenkel and Mihály Weiner,

Quantum 6, 662 (2022).

For a classical channel, neither the Shannon ca-pa-city, nor the sum of conditional probabilities corresponding to the cases of successful transmission can be increased by the use of shared…

Category: Paper