Article
Materials Science, Multidisciplinary
Hong-Yi Xie, Jaglul Hasan, Alex Levchenko
Summary: In this Letter, a detailed theoretical analysis is presented for the spectral properties of Andreev bound states in multiterminal Josephson junctions using a symmetry-constrained scattering matrix approach. It is found that crossings of Andreev bands in the synthetic multidimensional space of superconducting phases can support non-Abelian SU(2) monopoles characterized by the second class Chern number. The authors propose that these topological defects can be detected through a nonlinear response measurement of the current autocorrelations, and suggest that multiterminal Josephson junction devices can be tested as a hardware platform for holonomic quantum computation.
Article
Multidisciplinary Sciences
Jing-Ren Zhou, Qing-Rui Wang, Chenjie Wang, Zheng-Cheng Gu
Summary: Fractional statistics is a crucial feature in topological phases, especially in relation to topological quantum computation. This study explores three-loop braiding statistics in 3D interacting fermion systems, discovering new types of non-Abelian statistics. Additionally, the research proposes an alternative method for classifying fermionic symmetry-protected topological phases.
NATURE COMMUNICATIONS
(2021)
Article
Materials Science, Multidisciplinary
Brayden Ware, Dmitry Abanin, Romain Vasseur
Summary: In the field of many-body quantum dynamics, identifying nonergodic states beyond many-body localization (MBL) is a key challenge. Strongly disordered chains with non-Abelian symmetry may exhibit partially localized nonergodic behavior, characterized by entanglement entropy scaling as a logarithmically enhanced area law, according to real space renormalization group methods. These nonergodic states are found to be perturbatively unstable, with potential spontaneous symmetry breaking or ergodic thermal behavior at long times in strongly disordered chains with non-Abelian symmetry.
Article
Materials Science, Multidisciplinary
A. S. Osin, Ya. V. Fominov
Summary: This study focuses on a planar SIS-type Josephson junction and develops a fully self-consistent perturbation theory with respect to the interface conductance. The correction to the first Josephson harmonic and the calculation of the second Josephson harmonic are found as a result. Additionally, the perturbation theory corrects previous results for the nonsinusoidal current-phase relation in Josephson tunnel junctions and describes the difference between the phases of the order parameter and anomalous Green functions.
Article
Physics, Multidisciplinary
Li-Wei Yu, Dong-Ling Deng
Summary: This Letter introduces an unsupervised machine learning approach for classifying non-Hermitian topological phases, finding that the non-Hermitian skin effect poses an obstacle which can be overcome by choosing the correct input data. The results offer valuable guidance for future studies on unsupervised learning of non-Hermitian topological phases.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Meng-Qing Yu, Zhen-Gang Zhu, Gang Su
Summary: In this study, a Josephson junction setup consisting of intrinsic topological superconductors is proposed, in which the exchange operation of two Majorana zero modes (MZMs) can lead to a reversal of the single-electron tunneling current due to their non-Abelian statistics. This effect can be utilized to read out the initial qubit of the system, offering a way to demonstrate the non-Abelian statistical properties of MZMs.
Article
Nanoscience & Nanotechnology
Daniel Rodan-Legrain, Yuan Cao, Jeong Min Park, Sergio C. de la Barrera, Mallika T. Randeria, Kenji Watanabe, Takashi Taniguchi, Pablo Jarillo-Herrero
Summary: Magic-angle twisted bilayer graphene is a highly tunable two-dimensional material platform exhibiting a wide range of phases, such as metal, insulator and superconductor states. Local electrostatic gating devices enable versatile quantum devices like Josephson junctions, edge tunnelling spectroscopy, and single-electron transistor operation. By engineering Josephson junctions and tunnelling transistors solely defined by electrostatic gates, these devices show non-local electrodynamics in a magnetic field, paving the way for graphene-based tunable superconducting qubits and other applications.
NATURE NANOTECHNOLOGY
(2021)
Article
Optics
Julien Pinske, Stefan Scheel
Summary: This article investigates the generation of non-Abelian geometric phases from a system of evanescently coupled waveguides using nonorthogonal coupled-mode theory. A feasible tripod arrangement of waveguides is studied, which contains dark states that can undergo nontrivial U(2) mixing through an adiabatic parameter variation. The influence of higher-order contributions and self-coupling on the stability of a non-Abelian U(3) phase generated from an optical tetrapod setup is also examined. The results indicate that, despite the mode nonorthogonality, the symmetry of dark states protects the geometric evolution of light from distortion.
Article
Physics, Multidisciplinary
M. F. Araujo de Resende, J. P. Ibieta Jimenez, J. Lorca Espiro
Summary: Proving the importance of non-Abelian fusion rules in SPT phase transitions.
Article
Astronomy & Astrophysics
Yuki Fujimoto, Muneto Nitta
Summary: A recent proposal on quark-hadron continuity with two-flavor quarks has connected hadronic matter with neutron P-3(2) superfluidity and two-flavor dense quark matter. This new phase consists of the coexistence of 2SC condensates and P-wave diquark condensates, resulting in color superconductivity and superfluidity. Vortices in this phase are classified, with the most stable ones being non-Abelian Alice strings carrying orientational moduli of the real projective space RP2.
Article
Multidisciplinary Sciences
Heng Wu, Yaojia Wang, Yuanfeng Xu, Pranava K. Sivakumar, Chris Pasco, Ulderico Filippozzi, Stuart S. P. Parkin, Yu-Jia Zeng, Tyrel McQueen, Mazhar N. Ali
Summary: The Josephson diode, which serves as the superconducting analogue to the semiconducting diode, has been realized in a van der Waals heterostructure, showing unique properties such as magnetic-field-free superconductivity and different behaviors under positive and negative currents.
Article
Physics, Multidisciplinary
Jie Liu, Wenqin Chen, Ming Gong, Yijia Wu, XinCheng Xie
Summary: The complexity of braiding manipulation of Majorana zero modes (MZMs) has hindered its experimental realization. A proposed experimental setup with MZMs and a quantum dot state can simplify the braiding protocol of MZMs. The results of braiding can be measured through electric current, providing a novel way to detect the non-Abelian statistics of MZMs.
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(2021)
Article
Multidisciplinary Sciences
June-Young M. Lee, H-S Sim
Summary: A theoretical proposal for a collider for anyons has been reported, which can be used to explore the braiding statistics of various types of anyons. The collider's dominant process involves braiding between injected anyons and an anyon excited at the collider.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Multidisciplinary
Bruno Scheihing-Hitschfeld, Xiaojun Yao
Summary: Many transport coefficients of the quark-gluon plasma and nuclear structure functions can be expressed as gauge invariant correlation functions. The axial gauge n·A = 0 is discussed for calculating them, and the issues arising from trivializing the Wilson lines in correlation functions by gauge fixing are addressed. It is found that it is always impossible to completely remove the gauge fields n·A in Wilson lines that extend to infinity in the n direction by means of gauge transformations. The results explain the differences between two correlators defining transport coefficients and elucidate the discrepancies between two inequivalent gluon parton distribution functions.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Eduard Zsurka, Noel Plaszko, Peter Rakyta, Andor Kormanyos
Summary: We propose a device composed of two vertically stacked monolayer graphene Josephson junctions for Cooper pair splitting. The hybridization of Andreev bound states in the two Josephson junctions facilitates non-local transport in this normal-superconductor hybrid structure, as studied through the calculation of non-local differential conductance. Our setup offers the advantage of not requiring precise control over junction length, doping, or superconducting phase difference, making it potentially easier for experimental realization.
Editorial Material
Quantum Science & Technology
Markku Rasanen, Henrikki Makynen, Mikko Mottonen, Jan Goetz
Summary: Quantum computing has the potential to bring great economic prosperity to the European Union, but creating successful businesses in this field is challenging due to the required investments and infrastructure. The EU is making efforts to foster the quantum-computing ecosystem, proposing concrete actions for future growth and suggesting the creation of EU-based quantum-computing unicorns to drive technology and commercialization. These unicorns may serve as key points in pushing forward global policies and distinguishing the EU quantum ecosystem from others.
EPJ QUANTUM TECHNOLOGY
(2021)
Article
Physics, Multidisciplinary
P. Solinas, A. Amoretti, F. Giazotto
Summary: Since the 1960s, a deep and surprising connection between the development of superconductivity and quantum field theory has emerged, with examples such as the Anderson-Higgs mechanism and similarities between different equations. This parallelism predicts the superconducting Sauter-Schwinger effect, where electrostatic fields can create coherent excitations from the superconducting ground-state condensate. This phenomenon sheds light on the interaction between superconductors and electric fields and suggests a method for experimental verification.
PHYSICAL REVIEW LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Chengyu Yan, Juha Hassel, Visa Vesterinen, Jinli Zhang, Joni Ikonen, Leif Gronberg, Jan Goetz, Mikko Mottonen
Summary: The study presents an on-chip device based on a Josephson junction capable of coherent microwave emission, meeting the requirements for quantum-coherent operations. The characteristics of the device adhere to a perturbative theory based on a capacitively shunted Josephson junction, with low phase noise from the cryogenic microwave source resulting in infidelity lower than that caused by dephasing in superconducting qubits.
NATURE ELECTRONICS
(2021)
Article
Clinical Neurology
Juha-Matti Pirkkalainen, Anna-Stina Jaaskelainen, Paivi Halonen
Summary: In this study, researchers found that the performance status of elderly patients is the most important prognostic factor, and lower WHO status is associated with longer survival regardless of age. Additionally, methylated O(6)-methylguanine-DNA-methyltransferase and tumor resection are also correlated with better survival.
NEURO-ONCOLOGY PRACTICE
(2022)
Article
Physics, Applied
Tasio Gonzalez-Raya, Mateo Casariego, Florian Fesquet, Michael Renger, Vahid Salari, Mikko Mottonen, Yasser Omar, Frank Deppe, Kirill G. Fedorov, Mikel Sanz
Summary: Microwave technology plays a crucial role in wireless communications, and understanding its limitations in realistic open-air settings is important for its development. This study investigates the feasibility of open-air entanglement distribution with microwave two-mode squeezed states and explores techniques to improve quantum correlations and increase the reach of entanglement.
PHYSICAL REVIEW APPLIED
(2022)
Article
Physics, Applied
Federico Paolucci, Paolo Solinas, Francesco Giazotto
Summary: The L-SQUIPT is a design for an inductive superconducting quantum interference proximity transistor with enhanced performance, utilizing a double-loop structure and superconducting tunnel probe for improved coupling to external magnetic fields and increased characteristic magnetic flux transfer functions.
The behavior of L-SQUIPT is analyzed in both dissipative and dissipationless Josephson-like operation modes, showing potential for magnetic flux detection and specific applications in quantum technology.
PHYSICAL REVIEW APPLIED
(2022)
Article
Physics, Multidisciplinary
Toni Annala, Roberto Zamora-Zamora, Mikko Mottonen
Summary: This study presents research on topological knots and linked structures, constructs topologically protected links that cannot be untied through local reconnections, and proposes a classification scheme for topological vortex links.
COMMUNICATIONS PHYSICS
(2022)
Article
Instruments & Instrumentation
J. -P. Girard, R. E. Lake, W. Liu, R. Kokkoniemi, E. Visakorpi, J. Govenius, M. Mottonen
Summary: Recently, progress has been made in ultrasensitive microwave detectors, but their range of applications is limited due to a lack of compatibility with broad-band metrologically traceable power absorption measurements. In this study, an ultralow-noise nanobolometer with an additional dc heater input was used to make such measurements. The power absorption was traced by comparing the bolometer response between radio frequency and dc-heating powers traced to the Josephson voltage and quantum Hall resistance. The ability to accurately measure the attenuation of a coaxial input line between 50 MHz and 7 GHz with an uncertainty down to 0.1 dB at a typical input power of -114 dBm was demonstrated.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2023)
Review
Quantum Science & Technology
Mateo Casariego, Emmanuel Zambrini Cruzeiro, Stefano Gherardini, Tasio Gonzalez-Raya, Rui Andre, Goncalo Frazao, Giacomo Catto, Mikko Moettoenen, Debopam Datta, Klaara Viisanen, Joonas Govenius, Mika Prunnila, Kimmo Tuominen, Maximilian Reichert, Michael Renger, Kirill G. Fedorov, Frank Deppe, Harriet van der Vliet, A. J. Matthews, Yolanda Fernandez, R. Assouly, R. Dassonneville, B. Huard, Mikel Sanz, Yasser Omar
Summary: The field of propagating quantum microwaves is gaining attention for its promising technological applications in communication and sensing. Despite similarities with quantum optics, the development of a controllable quantum microwave interface is still in its early stages. This article argues for the need of a fully operative toolbox for propagating quantum microwaves, and explores novel directions of research such as microwave quantum key distribution, quantum radar, bath-system learning, and direct dark matter detection. It serves as both a review of the state-of-the-art and an illustration of the wide range of applications that quantum microwaves can offer in the future.
QUANTUM SCIENCE AND TECHNOLOGY
(2023)
Article
Physics, Multidisciplinary
Andrea Amoretti, Daniel K. Brattan, Nicodemo Magnoli, Luca Martinoia, Ioannis Matthaiakakis, Paolo Solinas
Summary: In this paper, a Ginzburg-Landau approach is used to investigate the phase transition from a superconductor to a normal metal under the influence of a strong electric field. The model considers corrections to the permittivity caused by the superconducting gap and takes into account screening effects. The experimental observations of the supercurrent control in superconducting thin films under a strong electric field are in excellent agreement with the model, and several observed features are successfully explained. Additionally, a method involving superconductor-superconductor electron tunneling is suggested to test the theoretical proposal.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Physics, Multidisciplinary
Toni Annala, Mikko Mottonen
Summary: This paper focuses on topological defects in mean-field-theory treatments of physical systems. The ambiguity and addition of topological charges are investigated using the mathematical formalism of covering spaces, clarifying many aspects of these phenomena. Topological-defect configurations consisting of several monopoles and unknotted ring defects are classified in terms of homotopy groups and fundamental-group actions, generalizing previous classifications. The decay of multiply charged topological monopoles under small perturbations and the conditions for their splitting into singly charged monopoles are analyzed.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Optics
P. Solinas, M. Amico, N. Zanghi
Summary: The study presents an approach to measure the averages of work, dissipated heat, and variation of internal energy of an open quantum system driven by an external classical field. By coupling a quantum detector to the system at different times, the full quantum features of the evolution are preserved. Obtaining quasicharacteristic functions and quasiprobability density functions from measured phases, despite not being directly measured, these functions can reproduce the expected values of physical quantities. The approach can distinguish between classical and quantum features, showing the disappearance of quantum features in the limit of fast dissipation and the emergence of the classical limit in the energy exchange process.
Article
Optics
P. Solinas, M. Amico, N. Zanghi
Summary: The research field studying the concepts of work and heat at the quantum level faces challenges in defining and measuring energy variations in quantum systems, and lack of experiments. A study using IBMQ quantum computer successfully characterized dissipated heat and work in a two-level quantum system, revealing the emergence of classical limit with increased environment coupling strength. This approach provides a valuable tool to study and exploit quantum effects in energy exchanges.
Article
Materials Science, Multidisciplinary
Vasilii Vadimov, Jani Tuorila, Tuure Orell, Juergen Stockburger, Tapio Ala-Nissila, Joachim Ankerhold, Mikko Mottonen
Summary: The research compared the applicability of different master equations in the case of resonant qubits transversely coupled to a Drude-cut ohmic bath, finding that weak-coupling methods have significant limitations in practical applications, requiring careful choice of modeling methods to ensure accuracy.
Article
Physics, Multidisciplinary
V. Vadimov, T. Hyart, J. L. Lado, M. Mottonen, T. Ala-Nissila
Summary: In this study, zero modes emerge in a many-body system without gauge symmetry breaking and in the absence of superconducting order, showing that robust Majorana-like zero modes may appear in a many-body system with no single-particle analogs.
PHYSICAL REVIEW RESEARCH
(2021)
