Quantum Science & Technology

Article Quantum Science & Technology

Towards practical quantum computers: transmon qubit with a lifetime approaching 0.5 milliseconds

Chenlu Wang, Xuegang Li, Huikai Xu, Zhiyuan Li, Junhua Wang, Zhen Yang, Zhenyu Mi, Xuehui Liang, Tang Su, Chuhong Yang, Guangyue Wang, Wenyan Wang, Yongchao Li, Mo Chen, Chengyao Li, Kehuan Linghu, Jiaxiu Han, Yingshan Zhang, Yulong Feng, Yu Song, Teng Ma, Jingning Zhang, Ruixia Wang, Peng Zhao, Weiyang Liu, Guangming Xue, Yirong Jin, Haifeng Yu

Summary: A breakthrough in fabricating a long lifetime transmon qubit was reported, using tantalum films as the base superconductor with a dry etching process. The transmon qubits achieved a best T-1 lifetime of 503 μs, outperforming those fabricated with niobium and aluminum. The stable and highly anisotropic dry etching process of tantalum film shows promise for fabricating medium- or large-scale superconducting quantum circuits with longer lifetimes, meeting the requirements for practical quantum computers.

NPJ QUANTUM INFORMATION (2022)

Article Quantum Science & Technology

Connecting Ansatz Expressibility to Gradient Magnitudes and Barren Plateaus

Zoe Holmes, Kunal Sharma, M. Cerezo, Patrick J. Coles

Summary: Parametrized quantum circuits are a flexible paradigm for solving variational problems and programming near-term quantum computers. By extending the barren plateau phenomenon to arbitrary ansatze, we establish a fundamental relationship between expressibility and trainability, showing that highly expressive ansatze are more difficult to train.

PRX QUANTUM (2022)

Article Quantum Science & Technology

Breaking the Rate-Loss Bound of Quantum Key Distribution with Asynchronous Two-Photon Interference

Yuan-Mei Xie, Yu-Shuo Lu, Chen-Xun Weng, Xiao-Yu Cao, Zhao-Ying Jia, Yu Bao, Yang Wang, Yao Fu, Hua-Lei Yin, Zeng-Bing Chen

Summary: In this study, an asynchronous measurement-device-independent quantum key distribution protocol is proposed, which can surpass the secret key capacity without phase tracking and phase locking. By leveraging the concept of time multiplexing, asynchronous two-photon Bell-state measurement is realized. The protocol has high key rates and transmission distance advantages compared to other protocols.

PRX QUANTUM (2022)

Article Quantum Science & Technology

Building a Fault-Tolerant Quantum Computer Using Concatenated Cat Codes

Christopher Chamberland, Kyungjoo Noh, Patricio Arrangoiz-Arriola, Earl T. Campbell, Connor T. Hann, Joseph Iverson, Harald Putterman, Thomas C. Bohdanowicz, Steven T. Flammia, Andrew Keller, Gil Refael, John Preskill, Liang Jiang, Amir H. Safavi-Naeini, Oskar Painter, Fernando G. S. L. Brandao

Summary: This paper presents a comprehensive architectural analysis for a fault-tolerant quantum computer based on cat codes combined with outer quantum error-correcting codes. The hardware proposed is a system of acoustic resonators coupled to superconducting circuits with a two-dimensional layout. Through detailed error analysis and numerical simulations, realistic estimates of the physical error rates and overheads needed to run fault-tolerant quantum algorithms are obtained. The study finds that with around 1000 superconducting circuit components, it is possible to construct a fault-tolerant quantum computer capable of running circuits currently intractable for classical computers.

PRX QUANTUM (2022)

Article Engineering, Electrical & Electronic

A significant role of MoO3 on the optical, thermal, and radiation shielding characteristics of B2O3-P2O5-Li2O glasses

Z. A. Alrowaili, Atif Mossad Ali, Ateyyah M. Al-Baradi, M. S. Al-Buriahi, E. A. Abdel Wahab, Kh S. Shaaban

Summary: In this study, a glass system was fabricated by adding varying concentrations of MoO3. The optical features, thermal properties, and radiation shielding ability of the glasses were examined. It was found that the addition of MoO3 can alter the optical and thermal properties of the glasses, as well as improve their radiation protection applications.

OPTICAL AND QUANTUM ELECTRONICS (2022)

Article Engineering, Electrical & Electronic

Optical solitons of nonlinear complex Ginzburg-Landau equation via two modified expansion schemes

Asim Zafar, Muhammad Shakeel, Asif Ali, Lanre Akinyemi, Hadi Rezazadeh

Summary: This article examines the complex Ginzburg-Landau equation with beta time derivative and analyzes its optical solitons and other solutions in the presence of a detuning factor in non-linear optics. Various solutions, including kink, bright, W-shaped bright, and dark solitons, are obtained using the modified Exp-function and Kudryshov methods. The model is examined in quadratic-cubic law, Kerr law, and parabolic laws non-linear fibers, and the restrictive conditions for the existence of solitons are presented. The obtained precise solutions are graphically displayed to illustrate the impact of non-linearity.

OPTICAL AND QUANTUM ELECTRONICS (2022)

Review Quantum Science & Technology

Quantum optimal control in quantum technologies. Strategic report on current status, visions and goals for research in Europe

Christiane P. Koch, Ugo Boscain, Tommaso Calarco, Gunther Dirr, Stefan Filipp, Steffen J. Glaser, Ronnie Kosloff, Simone Montangero, Thomas Schulte-Herbrueggen, Dominique Sugny, Frank K. Wilhelm

Summary: This paper reviews recent progress in the application and development of quantum optimal control in quantum technologies, and discusses future challenges and directions.

EPJ QUANTUM TECHNOLOGY (2022)

Article Quantum Science & Technology

Doubling the Size of Quantum Simulators by Entanglement Forging

Andrew Eddins, Mario Motta, Tanvi P. Gujarati, Sergey Bravyi, Antonio Mezzacapo, Charles Hadfield, Sarah Sheldon

Summary: This article presents a method called classical entanglement forging that uses classical resources to increase the size of systems that can be simulated on quantum hardware. By utilizing classical postprocessing, the researchers were able to simulate ten spin orbitals of the water molecule on five qubits of an IBM Quantum processor, achieving the most accurate variational simulation of the H2O ground-state energy using quantum hardware to date. The authors discuss the conditions for the applicability of classical entanglement forging and propose a roadmap for scaling up to larger problems.

PRX QUANTUM (2022)

Article Engineering, Electrical & Electronic

Free-Space Communication With Directly Modulated Mid-Infrared Quantum Cascade Devices

Olivier Spitz, Pierre Didier, Laureline Durupt, Daniel Andres Diaz-Thomas, Alexei N. Baranov, Laurent Cerutti, Frederic Grillot

Summary: This study examines the communication capabilities of two types of semiconductor lasers emitting in the 4 μm range of an atmosphere transparency window. The quantum cascade laser and interband cascade laser were used, with attenuation added to simulate free-space transmission. Different modulation formats were compared for maximum transmission data rate, and sensitivity to optical feedback and error rate were analyzed. The study provides insights into developing secure optical communication links using mid-infrared semiconductor lasers and highlights improvements needed for high-speed communication.

IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS (2022)

Article Materials Science, Multidisciplinary

Optical detection of the density-wave instability in the kagome metal KV3Sb5

Ece Uykur, Brenden R. Ortiz, Stephen D. Wilson, Martin Dressel, Alexander A. Tsirlin

Summary: In this study, we discover unconventional localized carriers with strong renormalization across the density-wave transition in KV3Sb5 through optical spectroscopy and density-functional calculations. We also observe strong phonon anomalies not only below the density-wave transition, but also at high temperatures, indicating a complex interplay between phonons and the underlying electronic structure. We propose star-of-David and tri-hexagon configurations for the density-wave order in KV3Sb5, which resemble the p-wave states expected in the Hubbard model on the kagome lattice with van Hove singularity filling.

NPJ QUANTUM MATERIALS (2022)

Review Astronomy & Astrophysics

The 4D Einstein-Gauss-Bonnet theory of gravity: a review

Pedro G. S. Fernandes, Pedro Carrilho, Timothy Clifton, David J. Mulryne

Summary: This review examines the recent interest in 4D Einstein-Gauss-Bonnet gravity, starting with an introduction to Lovelock's theorem and Gauss-Bonnet terms in gravity action. It discusses the mathematical complexities involved in including Gauss-Bonnet terms in four dimensions through rescaling the coupling parameter and reviews attempts to construct self-consistent theories. The review then explores the implications of 4D Einstein-Gauss-Bonnet gravity in black holes, cosmology, and weak-field gravity, highlighting interesting phenomena in each area.

CLASSICAL AND QUANTUM GRAVITY (2022)

Article Engineering, Electrical & Electronic

Application of new Kudryashov method to various nonlinear partial differential equations

Sandeep Malik, Mir Sajjad Hashemi, Sachin Kumar, Hadi Rezazadeh, W. Mahmoud, M. S. Osman

Summary: The purpose of this work is to find innovative exact solutions for nonlinear partial differential equations using the new Kudryashov approach. The technique provides novel exact solutions of soliton types. 3D and 2D plots of higher dimensional Klein-Gordon, Kadomtsev-Petviashvili, and Boussinesq equations are shown to better understand the nonlinear wave structures. The new Kudryashov technique is effective and simple, providing new generalized solitonic wave profiles that enhance the understanding of the development and dynamic nature of such models.

OPTICAL AND QUANTUM ELECTRONICS (2023)

Article Engineering, Electrical & Electronic

Dynamical behaviour of Chiral nonlinear Schrodinger equation

Lanre Akinyemi, Mustafa Inc, Mostafa M. A. Khater, Hadi Rezazadeh

Summary: In this work, the exact traveling wave solutions of the (2 + 1)-dimensional Chiral nonlinear Schrodinger equation were studied using the generalized auxiliary equation method. The results showed that the aforementioned model has wide applications in quantum field theory, and the suggested technique provides various types of solutions.

OPTICAL AND QUANTUM ELECTRONICS (2022)

Article Engineering, Electrical & Electronic

New optical solitons based on the perturbed Chen-Lee-Liu model through Jacobi elliptic function method

Sibel Tarla, Karmina K. Ali, Resat Yilmazer, M. S. Osman

Summary: In this study, the perturbed Chen-Lee-Liu equation, which describes the propagation of an optical pulse in plasma and optical fiber, was investigated. The Jacobi elliptic function technique was utilized, leading to the discovery of several new solitary wave solutions including the Jacobi elliptic function, dark-bright, trigonometric, exponential, hyperbolic, periodic, and singular soliton solutions. Specific values for the free parameters under conditions were also provided to express the pulse propagation of the generated solutions.

OPTICAL AND QUANTUM ELECTRONICS (2022)

Article Materials Science, Multidisciplinary

Possible star-of-David pattern charge density wave with additional modulation in the kagome superconductor CsV3Sb5

J. Luo, Z. Zhao, Y. Z. Zhou, J. Yang, A. F. Fang, H. T. Yang, H. J. Gao, R. Zhou, Guo-qing Zheng

Summary: In this study, the CDW order structure in the kagome superconductor CsV3Sb5 is investigated. It is found that the CDW order is of the first order, commensurate, and exhibits a star-of-David pattern. The experimental results provide new insights into AV(3)Sb(5).

NPJ QUANTUM MATERIALS (2022)

Article Materials Science, Multidisciplinary

Native point defects and their implications for the Dirac point gap at MnBi2Te4(0001)

M. Garnica, M. M. Otrokov, P. Casado Aguilar, I. I. Klimovskikh, D. Estyunin, Z. S. Aliev, I. R. Amiraslanov, N. A. Abdullayev, V. N. Zverev, M. B. Babanly, N. T. Mamedov, A. M. Shikin, A. Arnau, A. L. Vazquez de Parga, E. Chulkov, R. Miranda

Summary: We investigated the surface crystalline and electronic structures of the antiferromagnetic topological insulator MnBi2Te4 using STM/S, ARPES, and density functional theory calculations. Our findings reveal the presence of native point defects at the crystal surface and nonuniform defect concentrations within crystals and among different samples. Additionally, the experiments indicate that the Dirac point gap of the topological surface state varies among different samples and sample cleavages. Our calculations demonstrate that the antiparallel alignment of Mn-Bi moments can lead to a reduction in the Dirac point gap size. This study provides important insights into the debated issue of the MnBi2Te4 Dirac point gap.

NPJ QUANTUM MATERIALS (2022)

Article Astronomy & Astrophysics

Geometrization of light bending and its application to SdS w spacetime

Zhen Zhang

Summary: The mysterious dark energy remains one of the greatest puzzles of modern science, and its spacetime effects can be locally described by the SdS( w ) metric. Understanding these local effects exactly is an essential step toward the direct probe of dark energy. Through mathematical and conceptual analysis, it has been proven that dark energy can exert a repulsive dark force on astrophysical scales, which is different from the Newtonian attraction of both visible and dark matter.

CLASSICAL AND QUANTUM GRAVITY (2022)

Article Engineering, Electrical & Electronic

Non-Volatile Reconfigurable Silicon Photonics Based on Phase-Change Materials

Zhuoran Fang, Rui Chen, Jiajiu Zheng, Arka Majumdar

Summary: The use of phase change materials in silicon photonics has been gaining attention due to their high refractive index contrast between two states, which can be reversibly switched and non-volatile. Progress has been made in developing photonic switches based on PCM for photonic integrated circuits, showing great potential for future applications in this field.

IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS (2022)

Article Quantum Science & Technology

Microwave Engineering of Programmable XXZ Hamiltonians in Arrays of Rydberg Atoms

P. Scholl, H. J. Williams, G. Bornet, F. Wallner, D. Barredo, L. Henriet, A. Signoles, C. Hainaut, T. Franz, S. Geier, A. Tebben, A. Salzinger, G. Zuern, T. Lahaye, M. Weidemuller, A. Browaeys

Summary: This study utilizes the resonant dipole-dipole interaction between Rydberg atoms and a periodic microwave field to engineer XXZ spin Hamiltonians with tunable anisotropies. The experimental results demonstrate the potential applications of this technique in quantum simulation, quantum information processing, and quantum sensing.

PRX QUANTUM (2022)

Review Quantum Science & Technology

Quantum Communication Using Semiconductor Quantum Dots

Daniel A. Vajner, Lucas Rickert, Timm Gao, Koray Kaymazlar, Tobias Heindel

Summary: This article reviews the methods of constructing quantum light sources based on epitaxial semiconductor quantum dots and their applications in quantum communication. It provides an overview of the main concepts of quantum communication, introduces devices for single-photon and entangled-photon generation, and summarizes experimental implementations of quantum key distribution protocols using quantum dot based quantum light sources. Furthermore, recent progress in quantum-secured communication networks and their building blocks is summarized, and future directions and challenges in the field are discussed.

ADVANCED QUANTUM TECHNOLOGIES (2022)