QUROPE Quantum Information Processing and Communication in Europe

Author(s): Ye-Chao Liu, Jiangwei Shang, Rui Han, and Xiangdong Zhang

The efficient and reliable characterization of quantum states plays a vital role in most, if not all, quantum information processing tasks. In this work, we present a universally optimal protocol for verifying entangled states by employing the so-called quantum nondemolition measurements, such that ...

[Phys. Rev. Lett. 126, 090504] Published Thu Mar 04, 2021

Author(s): He-Liang Huang, Marek Narożniak, Futian Liang, Youwei Zhao, Anthony D. Castellano, Ming Gong, Yulin Wu, Shiyu Wang, Jin Lin, Yu Xu, Hui Deng, Hao Rong, Jonathan P. Dowling, Cheng-Zhi Peng, Tim Byrnes, Xiaobo Zhu, and Jian-Wei Pan

A multiqubit topological quantum protocol is implemented using a superconducting quantum simulator to braid non-Abelian anyons.

[Phys. Rev. Lett. 126, 090502] Published Wed Mar 03, 2021

Author(s): Eric I. Rosenthal, Christian M. F. Schneider, Maxime Malnou, Ziyi Zhao, Felix Leditzky, Benjamin J. Chapman, Waltraut Wustmann, Xizheng Ma, Daniel A. Palken, Maximilian F. Zanner, Leila R. Vale, Gene C. Hilton, Jiansong Gao, Graeme Smith, Gerhard Kirchmair, and K. W. Lehnert

Superconducting qubits are a leading platform for scalable quantum computing and quantum error correction. One feature of this platform is the ability to perform projective measurements orders of magnitude more quickly than qubit decoherence times. Such measurements are enabled by the use of quantum...

[Phys. Rev. Lett. 126, 090503] Published Wed Mar 03, 2021

Author(s): Xu-Jie Wang, Sheng-Jun Yang, Peng-Fei Sun, Bo Jing, Jun Li, Ming-Ti Zhou, Xiao-Hui Bao, and Jian-Wei Pan

A cold atomic ensemble suits well for optical quantum memories, and its entanglement with a single photon forms the building block for quantum networks that give promise for many revolutionary applications. Efficiency and lifetime are among the most important figures of merit for a memory. In this L...

[Phys. Rev. Lett. 126, 090501] Published Tue Mar 02, 2021

Author(s): Georg Engelhardt and Jianshu Cao

In recent experiments, the light-matter interaction has reached the ultrastrong coupling limit, which can give rise to dynamical generalizations of spatial symmetries in periodically driven systems. Here, we present a unified framework of dynamical-symmetry-protected selection rules based on Floquet...

[Phys. Rev. Lett. 126, 090601] Published Tue Mar 02, 2021

Author(s): Kang-Da Wu, Tulja Varun Kondra, Swapan Rana, Carlo Maria Scandolo, Guo-Yong Xiang, Chuan-Feng Li, Guang-Can Guo, and Alexander Streltsov

There exist real quantum states which can be perfectly distinguished via local operations and classical communication, but which cannot be distinguished with any nonzero probability if one of the parties has no access to imaginarity.

[Phys. Rev. Lett. 126, 090401] Published Mon Mar 01, 2021

Author(s): Gonzalo Manzano, Diego Subero, Olivier Maillet, Rosario Fazio, Jukka P. Pekola, and Édgar Roldán

In a new version of Maxwell’s demon, the tiny being plays the role of a gambler who knows when to quit.

[Phys. Rev. Lett. 126, 080603] Published Fri Feb 26, 2021

Author(s): Zhihong Ren, Weidong Li, Augusto Smerzi, and Manuel Gessner

We characterize metrologically useful multipartite entanglement by representing partitions with Young diagrams. We derive entanglement witnesses that are sensitive to the shape of Young diagrams and show that Dyson’s rank acts as a resource for quantum metrology. Common quantifiers, such as the enta...

[Phys. Rev. Lett. 126, 080502] Published Thu Feb 25, 2021

Author(s): Qiwei Yu, Dongliang Zhang, and Yuhai Tu

The energy dissipation rate in a nonequilibrium reaction system can be determined by the reaction rates in the underlying reaction network. By developing a coarse-graining process in state space and a corresponding renormalization procedure for reaction rates, we find that energy dissipation rate ha...

[Phys. Rev. Lett. 126, 080601] Published Tue Feb 23, 2021

Author(s): Yucheng Wang, Chen Cheng, Xiong-Jun Liu, and Dapeng Yu

The transition between ergodic and many-body localization (MBL) phases lies at the heart of understanding quantum thermalization of many-body systems. Here, we predict a many-body critical (MBC) phase with finite-size scaling analysis in the one-dimensional extended Aubry-André-Harper-Hubbard model,...

[Phys. Rev. Lett. 126, 080602] Published Tue Feb 23, 2021

Author(s): Zhen Wang, Yanzhu Chen, Zixuan Song, Dayue Qin, Hekang Li, Qiujiang Guo, H. Wang, Chao Song, and Ying Li

A major challenge in developing quantum computing technologies is to accomplish high precision tasks by utilizing multiplex optimization approaches, on both the physical system and algorithm levels. Loss functions assessing the overall performance of quantum circuits can provide the foundation for m...

[Phys. Rev. Lett. 126, 080501] Published Mon Feb 22, 2021

Author(s): Lucas T. Brady, Christopher L. Baldwin, Aniruddha Bapat, Yaroslav Kharkov, and Alexey V. Gorshkov

Quantum annealing (QA) and the quantum approximate optimization algorithm (QAOA) are two special cases of the following control problem: apply a combination of two Hamiltonians to minimize the energy of a quantum state. Which is more effective has remained unclear. Here we analytically apply the fra...

[Phys. Rev. Lett. 126, 070505] Published Fri Feb 19, 2021

Author(s): S. Pegahan, I. Arakelyan, and J. E. Thomas

Weakly interacting Fermi gases simulate spin lattices in energy space, offering a rich platform for investigating information spreading and spin coherence in a large many-body quantum system. We show that the collective spin vector can be determined as a function of energy from the measured spin den...

[Phys. Rev. Lett. 126, 070601] Published Fri Feb 19, 2021

Author(s): Bin Yan, Vladimir Y. Chernyak, Wojciech H. Zurek, and Nikolai A. Sinitsyn

A spin system crossing a quantum phase transition nonadiabatically may undergo exponential suppression of excitations in the presence of asymmetries.

[Phys. Rev. Lett. 126, 070602] Published Fri Feb 19, 2021

Author(s): Jacopo Valsecchi, Malgorzata G. Makowska, Youngju Kim, Seung Wook Lee, Christian Grünzweig, Florian M. Piegsa, Michel A. Thijs, Jeroen Plomp, and Markus Strobl

We have recently shown how a polarized beam in Talbot-Lau interferometric imaging can be used to analyze strong magnetic fields through the spin dependent differential phase effect at field gradients. While in that case an adiabatic spin coupling with the sample field is required, here we investigat...

[Phys. Rev. Lett. 126, 070401] Published Thu Feb 18, 2021

Author(s): X. Fan and G. Gabrielse

Detector backaction can be completely evaded when the state of a one-electron quantum cyclotron is detected, but it nonetheless significantly broadens the quantum-jump resonance line shapes from which the cyclotron frequency can be deduced. This limits the accuracy with which the electron magnetic m...

[Phys. Rev. Lett. 126, 070402] Published Thu Feb 18, 2021

Author(s): Zhibo Hou, Yan Jin, Hongzhen Chen, Jun-Feng Tang, Chang-Jiang Huang, Haidong Yuan, Guo-Yong Xiang, Chuan-Feng Li, and Guang-Can Guo

The Heisenberg scaling, which scales as N−1 in terms of the number of particles or T−1 in terms of the evolution time, serves as a fundamental limit in quantum metrology. Better scalings, dubbed as “super-Heisenberg scaling,” however, can also arise when the generator of the parameter involves many-...

[Phys. Rev. Lett. 126, 070503] Published Thu Feb 18, 2021

Author(s): Scott E. Smart and David A. Mazziotti

The accurate computation of ground and excited states of many-fermion quantum systems is one of the most consequential, contemporary challenges in the physical and computational sciences whose solution stands to benefit significantly from the advent of quantum computing devices. Existing methodologi...

[Phys. Rev. Lett. 126, 070504] Published Thu Feb 18, 2021

Author(s): R. Ito, S. Takada, A. Ludwig, A. D. Wieck, S. Tarucha, and M. Yamamoto

We develop a coherent beam splitter for single electrons driven through two tunnel-coupled quantum wires by surface acoustic waves (SAWs). The output current through each wire oscillates with gate voltages to tune the tunnel coupling and potential difference between the wires. This oscillation is as...

[Phys. Rev. Lett. 126, 070501] Published Tue Feb 16, 2021

Author(s): Chu Guo, Youwei Zhao, and He-Liang Huang

The ability to efficiently simulate random quantum circuits using a classical computer is increasingly important for developing noisy intermediate-scale quantum devices. Here, we present a tensor network states based algorithm specifically designed to compute amplitudes for random quantum circuits w...

[Phys. Rev. Lett. 126, 070502] Published Tue Feb 16, 2021