QUROPE Quantum Information Processing and Communication in Europe

Author(s): Harry E. Dyte, George Gillard, Santanu Manna, Saimon F. Covre da Silva, Armando Rastelli, and Evgeny A. Chekhovich

The measurement problem dates back to the dawn of quantum mechanics. Here, we measure a quantum dot electron spin qubit through off-resonant coupling with a highly redundant ancilla, consisting of thousands of nuclear spins. Large redundancy allows for single-shot measurement with high fidelity ≈99.…

[Phys. Rev. Lett. 132, 160804] Published Fri Apr 19, 2024

Author(s): Matthew Sullivan

The [[7,1,3]] Steane code and [[23,1,7]] quantum Golay code have been identified as good candidates for fault-tolerant quantum computing via code concatenation. These two codes have transversal implementations of all Clifford gates but require some other scheme for fault-tolerant T gates. Using magi…

[Phys. Rev. A 109, 042416] Published Thu Apr 18, 2024

Author(s): Qing-Shou Tan, Xulin Liu, Lan Xu, Wei Wu, and Le-Man Kuang

We present a quantum thermometry method utilizing a probe-meter system and leveraging reinforcement learning (RL) to enhance sensitivity at low temperatures. Temperature information is exclusively obtained by coupling the probe qubit with the bath, facilitating efficient information extraction by m…

[Phys. Rev. A 109, 042417] Published Thu Apr 18, 2024

Author(s): Albert T. Schmitz, Nicolas P. D. Sawaya, Sonika Johri, and A. Y. Matsuura

Hamiltonian simulation represents an important module in a large class of quantum algorithms and simulations such as quantum machine learning, quantum linear algebra methods, and modeling for physics, material science, and chemistry. One of the most prominent methods for realizing the time-evolution…

[Phys. Rev. A 109, 042418] Published Thu Apr 18, 2024

Author(s): Tirth Shah, Christian Brendel, Vittorio Peano, and Florian Marquardt

Artificially engineered mechanical systems, sometimes called metamaterials, offer many promising applications on length scales ranging from macroscopic systems to the nanoscale. A topic of particular interest is the existence of topologically protected phononic edge states in such systems that are analogous to the electronic edge states that give rise to the quantum Hall effect. This Colloquium gives an introduction to topologically protected transport in metamaterials and its applications for controlling acoustic transport.

[Rev. Mod. Phys. 96, 021002] Published Thu Apr 18, 2024

Author(s): Ben Craps, Oleg Evnin, and Gabriele Pascuzzi

Krylov complexity and Nielsen complexity are successful approaches to quantifying quantum evolution complexity that have been actively pursued without much contact between the two lines of research. The two quantities are motivated by quantum chaos and quantum computation, respectively, while the re…

[Phys. Rev. Lett. 132, 160402] Published Thu Apr 18, 2024

Author(s): Yanbo Lou, Yinghui Lv, Jiabin Wang, Shengshuai Liu, and Jietai Jing

Quantum telecloning, a pivotal multiuser quantum communication protocol in the realm of quantum information science, facilitates the copy of a quantum state across M distinct locations through teleportation technique. In the continuous-variable regime, the implementation of quantum telecloning neces…

[Phys. Rev. Lett. 132, 160803] Published Thu Apr 18, 2024

Author(s): Alexey Uvarov and Dmitry Vinichenko

Gaussian boson samplers aim to demonstrate quantum advantage by performing a sampling task believed to be classically hard. The probabilities of individual outcomes in the sampling experiment are determined by the Hafnian of an appropriately constructed symmetric matrix. For non-negative matrices, t…

[Phys. Rev. A 109, 042415] Published Wed Apr 17, 2024

Author(s): Yu Guo, Zixuan Liu, Hao Tang, Xiao-Min Hu, Bi-Heng Liu, Yun-Feng Huang, Chuan-Feng Li, Guang-Can Guo, and Giulio Chiribella

Quantum theory allows information to flow through a single device in a coherent superposition of two opposite directions, resulting into situations where the input-output direction is indefinite. Here we introduce a theoretical method to witness input-output indefiniteness in a single quantum device…

[Phys. Rev. Lett. 132, 160201] Published Tue Apr 16, 2024

Author(s): Davide Rattacaso, Gianluca Passarelli, Angelo Russomanno, Procolo Lucignano, Giuseppe E. Santoro, and Rosario Fazio

Finding a local Hamiltonian H^ that has a given many-body wave function |ψ⟩ as its ground state, i.e., a parent Hamiltonian, is a challenge of fundamental importance in quantum technologies. Here we introduce a numerical method, inspired by quantum annealing, that efficiently performs this task thro…

[Phys. Rev. Lett. 132, 160401] Published Tue Apr 16, 2024

Author(s): Alessia Suprano, Danilo Zia, Luca Innocenti, Salvatore Lorenzo, Valeria Cimini, Taira Giordani, Ivan Palmisano, Emanuele Polino, Nicolò Spagnolo, Fabio Sciarrino, G. Massimo Palma, Alessandro Ferraro, and Mauro Paternostro

Measuring a photon’s angular momentum after it passes through optical devices teaches an algorithm to reconstruct the properties of the photon’s initial quantum state.

[Phys. Rev. Lett. 132, 160802] Published Tue Apr 16, 2024

Author(s): Subhayan Sahu and Shao-Kai Jian

We study the emergence of anticoncentration and approximate unitary design behavior in local Brownian circuits. The dynamics of circuit-averaged moments of the probability distribution and entropies of the output state can be represented as imaginary-time evolution with an effective local Hamiltonia…

[Phys. Rev. A 109, 042414] Published Mon Apr 15, 2024

Author(s): Ren-Zhou Fang, Xiao-Yi Lai, Tao Li, Ren-Zhu Su, Bo-Wei Lu, Chao-Wei Yang, Run-Ze Liu, Yu-Kun Qiao, Cheng Li, Zhi-Gang He, Jia Huang, Hao Li, Li-Xing You, Yong-Heng Huo, Xiao-Hui Bao, and Jian-Wei Pan

A solid-state approach for quantum networks is advantageous, as it allows the integration of nanophotonics to enhance the photon emission and the utilization of weakly coupled nuclear spins for long-lived storage. Silicon carbide, specifically point defects within it, shows great promise in this reg…

[Phys. Rev. Lett. 132, 160801] Published Mon Apr 15, 2024

Author(s): Christopher K. Long, Kieran Dalton, Crispin H. W. Barnes, David R. M. Arvidsson-Shukur, and Normann Mertig

Adaptive variational quantum eigensolvers (ADAPT-VQEs) are promising candidates for simulations of strongly correlated systems on near-term quantum hardware. To further improve the noise resilience of these algorithms, recent efforts have been directed towards compactifying, or layering, their Ansat…

[Phys. Rev. A 109, 042413] Published Fri Apr 12, 2024

Author(s): He-Ran Wang, Dong Yuan, Shun-Yao Zhang, Zhong Wang, Dong-Ling Deng, and L.-M. Duan

Quantum many-body scars are nonthermal excited eigenstates of nonintegrable Hamiltonians, which could support coherent revival dynamics from special initial states when scars form an equally spaced tower in the energy spectrum. For open quantum systems, engineering many-body scarred dynamics by a co…

[Phys. Rev. Lett. 132, 150401] Published Fri Apr 12, 2024

Author(s): Dany Lachance-Quirion, Marc-Antoine Lemonde, Jean Olivier Simoneau, Lucas St-Jean, Pascal Lemieux, Sara Turcotte, Wyatt Wright, Amélie Lacroix, Joëlle Fréchette-Viens, Ross Shillito, Florian Hopfmueller, Maxime Tremblay, Nicholas E. Frattini, Julien Camirand Lemyre, and Philippe St-Jean

The Gottesman-Kitaev-Preskill (GKP) code encodes a logical qubit into a bosonic system with resilience against single-photon loss, the predominant error in most bosonic systems. Here we present experimental results demonstrating quantum error correction of GKP states based on reservoir engineering o…

[Phys. Rev. Lett. 132, 150607] Published Fri Apr 12, 2024

Author(s): Shu-Qian Liu, Lu Wang, Hao Fan, Feng-Lin Wu, and Si-Yuan Liu

We construct a central-spin battery model affected by noise or thermal bath and consider the impact of environment on battery performance. In a noisy environment, we show that the steady-state energy and ergotropy are related to the number of spins exposed to the noisy channel. In addition, we revea…

[Phys. Rev. A 109, 042411] Published Thu Apr 11, 2024

Author(s): Joseph G. Smith, Crispin H. W. Barnes, and David R. M. Arvidsson-Shukur

Quantum-phase-estimation algorithms are critical subroutines in many applications for quantum computers and in quantum-metrology protocols. These algorithms estimate the unknown strength of a unitary evolution. By using coherence or entanglement to sample the unitary Ntot times, the variance of the …

[Phys. Rev. A 109, 042412] Published Thu Apr 11, 2024

Author(s): S. Pucher, V. Klüsener, F. Spriestersbach, J. Geiger, A. Schindewolf, I. Bloch, and S. Blatt

We demonstrate coherent control of the fine-structure qubit in neutral strontium atoms. This qubit is encoded in the metastable P23 and P03 states, coupled by a Raman transition. Using a magnetic quadrupole transition, we demonstrate coherent state initialization of this THz qubit. We show Rabi osci…

[Phys. Rev. Lett. 132, 150605] Published Thu Apr 11, 2024

Author(s): G. Unnikrishnan, P. Ilzhöfer, A. Scholz, C. Hölzl, A. Götzelmann, R. K. Gupta, J. Zhao, J. Krauter, S. Weber, N. Makki, H. P. Büchler, T. Pfau, and F. Meinert

We report on the first realization of a novel neutral atom qubit encoded in the spin-orbit coupled metastable states P03 and P23 of a single Sr88 atom trapped in an optical tweezer. Raman coupling of the qubit states promises rapid single-qubit rotations on par with the fast Rydberg-mediated two-bod…

[Phys. Rev. Lett. 132, 150606] Published Thu Apr 11, 2024