Article
Quantum Science & Technology
Iivari Pietikainen, Ondrej Cernotik, Shruti Puri, Radim Filip, S. M. Girvin
Summary: In hybrid circuit quantum electrodynamics, a controlled beam splitter gate is a powerful resource for creating ancilla-controlled SWAP gates, executing swap tests, preparing quantum non-Gaussian entanglement, and measuring nonlinear functionals of quantum states. A new realization of a hybrid cSWAP using "Kerr-cat" qubits offers important benefits for quantum computation.
QUANTUM SCIENCE AND TECHNOLOGY
(2022)
Article
Physics, Applied
Konstantin N. Nesterov, Chen Wang, Vladimir E. Manucharyan, Maxim G. Vavilov
Summary: We analyze the cross-resonance effect for fluxonium circuits and propose a two-qubit gate scheme based on selective darkening of a transition. By applying two microwave pulses at the target qubit frequency with a proper amplitude ratio, a controlled-NOT operation can be achieved. Gate error is calculated, and with the consideration of nonunitary effects, gate error below 10^-4 is shown to be possible for realistic hardware parameters.
PHYSICAL REVIEW APPLIED
(2022)
Article
Optics
Ibukunoluwa A. Adisa, Thomas G. Wong
Summary: This paper explores converting quantum gates into dynamic quantum walks and reducing the long sequences of graphs that may result from the conversion process. A length-3 dynamic quantum walk is proposed to implement single-qubit gates, and this is further extended to implement single-qubit gates controlled by any number of qubits. Using these results, Draper's quantum addition circuit based on the quantum Fourier transform is successfully implemented using a dynamic quantum walk.
Article
Chemistry, Physical
Edoardo G. Carnio, Andreas Buchleitner, Frank Schlawin
Summary: This study investigates optimal states of photon pairs to excite a target transition in a multilevel quantum system, demonstrating that quantum correlations can enhance selectivity between two energy levels, especially with broadening linewidths of the target states.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Quantum Science & Technology
Hilal A. Bhat, Farooq A. Khanday, B. K. Kaushik
Summary: This paper presents novel and efficient controlled adder/subtractor designs using reversible quantum computing and matrix modeling approach. Significant improvements in performance parameters have been achieved, with optimized quantum cost improvements of up to 31.25%. The proposed designs are found to be more efficient than existing separate adder/subtractor and combined designs.
QUANTUM INFORMATION PROCESSING
(2023)
Article
Optics
Adenilton J. da Silva, Daniel K. Park
Summary: The paper presents a systematic procedure for decomposing multiqubit controlled unitary gates into controlled -NOT and single-qubit gates to minimize quantum circuit depth. The algorithm does not require ancillary qubits and achieves a quadratic reduction in circuit depth compared to known methods.
Article
Physics, Multidisciplinary
Yu-Hong Han, Cong Cao, Ling Fan, Ru Zhang
Summary: In this paper, a potentially practical scheme for implementing nonlocal quantum controlled-not (CNOT) gate operations on quantum-dot-confined electron spins between two quantum network nodes is presented. The scheme utilizes hyperentangled photon pairs to establish a quantum channel, enabling parallel teleportation of two nonlocal quantum CNOT gates simultaneously and improving channel capacity and operational speed. The scheme is efficient, robust, and can be used as a universal module for other quantum information processing tasks.
FRONTIERS IN PHYSICS
(2022)
Article
Physics, Multidisciplinary
J. L. Lopez-Picon, J. Manuel Lopez-Vega
Summary: This study revisits the thermodynamic geometry of the Bose-Einstein fluid within the framework of information geometry, particularly considering the strongly degenerate case for a finite volume. The ground state contribution is found to be relevant in highly quantum conditions, affecting the scalar curvature R in the limit of condensation. The curvature is shown to be finite and approach zero smoothly as the fugacity tends to the numerical value where condensation occurs, indicating stronger quantum effects.
PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS
(2021)
Article
Quantum Science & Technology
Sven Jandura, Guido Pupillo
Summary: In this study, we identify time-optimal laser pulses for implementing the controlled-Z gate and its generalization, the C(2)Z gate, for Rydberg atoms. The pulses are optimized using quantum optimal control techniques, resulting in smooth waveforms with only a few variational parameters. The short gate duration helps mitigate errors while achieving theoretical gate fidelities compatible with error correction.
Article
Quantum Science & Technology
Sven Jandura, Jeff D. Thompson, Guido Pupillo
Summary: Researchers introduced a new gate sequence that is robust against intensity inhomogeneity and Doppler shifts, reducing the sensitivity of gate operations in neutral-atom qubits to experimental imperfections. The gates outperform existing ones for moderate or large imperfections, and show improved performance even for very small imperfections when applied to erasure-biased qubits based on metastable 171Yb.
Article
Quantum Science & Technology
Shannon Whitlock
Summary: A simple scheme is proposed for robust optically controlled quantum gates in scalable atomic quantum processors. By driving the qubits with optical standing waves, phase-controlled quantum operations can be realized near the antinodes of the standing wave, which are less sensitive to local optical phase and atomic motion compared to travelling wave configurations. The scheme is compatible with robust optimal control techniques and spatial qubit addressing in atomic arrays, enabling phase controlled operations without tight focusing and precise positioning of control lasers. This provides an all optical route to scaling up atomic quantum processors, particularly beneficial for quantum gates involving Doppler sensitive optical frequency transitions.
Article
Optics
T. H. Xing, P. Z. Zhao, D. M. Tong
Summary: This paper presents a scheme for implementing nonadiabatic holonomic multiqubit controlled gates based on Rydberg atoms, where the Rydberg-mediated interaction couples two qubits and allows for the implementation of quantum gates in a short duration. The effective coupling between two qubits is in the first-order strength of Rabi frequencies, enabling the realization of quantum gates efficiently.
Article
Multidisciplinary Sciences
Andrei Tanasescu, David Constantinescu, Pantelimon George Popescu
Summary: The author proposed a distributed quantum computation protocol for small register devices, enabling the distribution of controlled unitary gates and leveraging quantum sharing of partial results for parallel processing, achieving for the first time the quantum distribution of very large gates using small register devices.
SCIENTIFIC REPORTS
(2022)
Article
Physics, Applied
Li-Na Sun, L-L Yan, Shi-Lei Su, Y. Jia
Summary: We propose a one-step scheme to implement time-optimal nonadiabatic holonomic three-qubit controlled gates in Rydberg atoms, achieving significant reductions in evolution time and higher fidelity and robustness. This scheme is also independent of specific physical platforms, potentially allowing for wider applications.
PHYSICAL REVIEW APPLIED
(2021)
Article
Nanoscience & Nanotechnology
Juhyeon Kim, Zachary Croft, Duncan G. Steel, Pei-Cheng Ku
Summary: This paper analyzes two laterally positioned quantum dot single-photon emitters in different semiconductor heterostructures. A controlled phase gate between two quantum dot spins based on Coulomb interaction is demonstrated. Increasing the bitrion coupling and spacing between the quantum dots improves the gate fidelity. The study also shows an enhanced bitrion coupling in In(Ga)N quantum dots.
Article
Physics, Multidisciplinary
Tengfang Kuang, Ran Huang, Wei Xiong, Yunlan Zuo, Xiang Han, Franco Nori, Cheng-Wei Qiu, Hui Luo, Hui Jing, Guangzong Xiao
Summary: Recently, a phonon laser based on dispersive optomechanical coupling has been demonstrated. This laser device allows flexible control of large-mass objects and reduces noise in high vacuum. However, achieving phonon lasing with micro-scale objects is still challenging.
Article
Physics, Multidisciplinary
Li-Bao Fan, Chuan-Cun Shu, Daoyi Dong, Jun He, Niels E. Henriksen, Franco Nori
Summary: We present a combined analytical and numerical study for coherent terahertz control of a single molecular polariton. We derive an analytical solution of a pulse-driven quantum Jaynes-Cummings model to achieve complete quantum coherent control of the polariton. This study offers a new strategy to study rotational dynamics in the strong-coupling regime and has direct applications in polariton chemistry and molecular polaritonics.
PHYSICAL REVIEW LETTERS
(2023)
Review
Physics, Multidisciplinary
Oleh V. Ivakhnenko, Sergey N. Shevchenko, Franco Nori
Summary: This article systematically studies various aspects of LZSM physics and reviews the relevant literature, significantly expanding on the previous review article. The interfernce between transitions in LZSM has recently become accessible, controllable, and useful for manipulating a growing number of quantum systems.
PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS
(2023)
Article
Multidisciplinary Sciences
Ievgen I. I. Arkhipov, Adam Miranowicz, Fabrizio Minganti, Sahin K. Ozdemir, Franco Nori
Summary: Nontrivial spectral properties of non-Hermitian systems can lead to intriguing effects, such as controlled asymmetric-symmetric mode switching in a two-mode photonic system by dynamically winding around an exceptional point (EP). However, for multimode systems with higher-order EPs or multiple low-order EPs, controlling asymmetric-symmetric mode switching can be impeded due to the breakdown of adiabaticity. In this work, we demonstrate that this difficulty can be overcome by winding around exceptional curves by additionally crossing diabolic points. Our findings provide alternative routes for light manipulations in non-Hermitian photonic setups.
NATURE COMMUNICATIONS
(2023)
Article
Multidisciplinary Sciences
Midya Parto, Christian Leefmans, James Williams, Franco Nori, Alireza Marandi
Summary: The researchers demonstrate that photonic topological lattices with dissipative couplings can exhibit non-Abelian dynamics and geometric phases, contrasting with energy-conserving systems. Topology plays a central role in various fields, and its study has extended to open systems, leading to fascinating effects such as topological lasing and exceptional surfaces. They show that the geometric properties of Bloch eigenstates in dissipatively coupled lattices cannot be described by scalar Berry phases, unlike conservative Hamiltonians. This behavior is attributed to significant population exchanges among dissipation bands. The researchers provide theoretical and experimental evidence that such exchanges manifest as matrix-valued operators in Bloch dynamics, resulting in non-commuting pairs and non-Abelian dynamics in two-dimensional lattices.
NATURE COMMUNICATIONS
(2023)
Review
Physics, Multidisciplinary
Bin Cheng, Xiu-Hao Deng, Xiu Gu, Yu He, Guangchong Hu, Peihao Huang, Jun Li, Ben-Chuan Lin, Dawei Lu, Yao Lu, Chudan Qiu, Hui Wang, Tao Xin, Shi Yu, Man-Hong Yung, Junkai Zeng, Song Zhang, Youpeng Zhong, Xinhua Peng, Franco Nori, Dapeng Yu
Summary: In the past decade, quantum computers have made remarkable progress and achieved key milestones towards universal fault-tolerant quantum computers. Quantum hardware has become more integrated and architectural, surpassing the fault-tolerant threshold in controlling various physical systems. Quantum computation research has embraced industrialization and commercialization, shaping a vibrant environment that accelerates the development of this field, now in the noisy intermediate-scale quantum era.
FRONTIERS OF PHYSICS
(2023)
Article
Multidisciplinary Sciences
Shuai-Peng Wang, Alessandro Ridolfo, Tiefu Li, Salvatore Savasta, Franco Nori, Y. Nakamura, J. Q. You
Summary: Hybrid quantum systems in the ultrastrong and deep-strong coupling regimes exhibit exotic physical phenomena and have potential applications in quantum technologies. In these nonperturbative regimes, a qubit-resonator system has an entangled quantum vacuum with virtual photons that cannot be directly detected. However, the vacuum field can induce symmetry breaking of a dispersively coupled probe qubit. Wang et al. experimentally observe parity symmetry breaking in a probe qubit coupled to a deep-strongly coupled resonator, providing a way to explore novel quantum-vacuum effects.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
A. L. Rakhmanov, A. Rozhkov, A. O. Sboychakov, Franco Nori
Summary: We argue theoretically that electron-electron coupling in doped AB bilayer graphene can lead to the spontaneous formation of fractional metal phases. These states, which are generalizations of a more common half-metal, have a fully polarized Fermi surface in terms of both spin-related quantum number and valley index. Our proposed mechanism suggests that undoped bilayer graphene is a spin-density-wave insulator and upon doping, transitions to fractional metal phases occur. Our findings are consistent with recent experiments on doped AB bilayer graphene that observed phase transitions between different isospin states.
Article
Materials Science, Multidisciplinary
Zi-Yong Ge, Franco Nori
Summary: We study a spin-1/2 fermion chain coupled to a Z2 gauge field and analyze the effects of electric fields on low-energy excitations. In the half-filling case, the system remains a Mott insulator despite the presence of electric fields. For hole-doped systems, holes are confined under nonzero electric fields, leading to the formation of hole-pair bound states. These bound states significantly influence superconductivity, demonstrating the emergence of attractive interactions between bond-singlet Cooper pairs. Furthermore, lattice fermion confinement induced by electric fields enhances the superconducting instability. Our findings provide insights into unconventional superconductivity in Z2 lattice gauge theories and have implications for experimental investigation in quantum simulators.
Article
Physics, Multidisciplinary
Enrico Russo, Alberto Mercurio, Fabio Mauceri, Rosario Lo Franco, Franco Nori, Salvatore Savasta, Vincenzo Macri
Summary: The study finds that, within currently available experimental parameters, there is photon-pair hopping between two cavities separated by a vibrating two-sided perfect mirror. This hopping is not due to tunneling, but rather to higher-order resonant processes. This discovery opens up the possibility to investigate a new mechanism of photon-pair propagation in optomechanical lattices.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Optics
Tenzan Araki, Franco Nori, Clemens Gneiting
Summary: The theory of optimal quantum control plays a vital role in the design and development of quantum technologies by identifying control Hamiltonians that efficiently produce desired target states. However, control pulses are often sensitive to small perturbations, making it difficult to deploy them reliably in experiments. Robust quantum control aims to find control pulses that can reproduce target states even in the presence of perturbations. In this study, we propose a method based on disorder-dressed evolution equations to identify robust control pulses, which capture the effect of perturbations through quantum master equations. We demonstrate the effectiveness of this method in several single-qubit control tasks using a modified version of Krotov's method.
Article
Physics, Multidisciplinary
Neill Lambert, Tarun Raheja, Simon Cross, Paul Menczel, Shahnawaz Ahmed, Alexander Pitchford, Daniel Burgarth, Franco Nori
Summary: The hierarchical equations of motion (HEOM) method is a powerful numerical approach to solve the dynamics and find the steady-state of a quantum system coupled to a non-Markovian and nonperturbative environment. It has been applied to various areas including physical chemistry, solid-state physics, optics, single-molecule electronics, and biological physics. We present a numerical library in Python that implements the HEOM for both bosonic and fermionic environments, integrated with the QuTiP platform. Rating: 8/10.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Physics, Multidisciplinary
Kuan-Yi Lee, Jhen-Dong Lin, Adam Miranowicz, Franco Nori, Huan-Yu Ku, Yueh-Nan Chen
Summary: Quantum steering is a significant correlation in quantum information theory and has been found to be useful for quantum metrology. This study extends the exploration of steering-enhanced quantum metrology from single noiseless phase shifts to superpositions of noisy phase shifts. Experimental results demonstrate that utilizing superpositions of noisy phase shifts can effectively suppress noise effects and improve metrology.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
Masaki Tezuka, Onur Oktay, Enrico Rinaldi, Masanori Hanada, Franco Nori
Summary: The sparse version of the Sachdev-Ye-Kitaev model reduces the number of disorder parameters while reproducing essential features of the original model. In this Research Letter, a further simplification called the binary-coupling sparse SYK model is proposed. This model sets the nonzero couplings to be +/- 1 instead of sampling from a continuous distribution. Remarkably, this simplification improves the model's performance in terms of exhibiting strong correlations in the spectrum and efficiently achieving random-matrix universality with fewer nonzero terms. Due to its simplicity and scaling properties, this model is better suited for quantum simulations of chaotic behavior and holographic metals.
Article
Materials Science, Multidisciplinary
Qian Bin, Liang-Liang Wan, Franco Nori, Ying Wu, Xin-You Lue
Summary: We propose a physical witness for detecting topological phase transitions (TPTs) using an experimentally observable out-of-time-order correlation (OTOC). The OTOC dynamics can distinguish between topological trivial and nontrivial phases due to topological locality. In the long-time limit, the OTOC undergoes a zero-to-finite-value transition at the critical point of the TPTs. This proposed OTOC witness is robust and can be applied to systems with and without chiral symmetry, even in the presence of disorder.
