Article
Optics
Liang Mao, Yajiang Hao, Lei Pan
Summary: In this paper, the non-Hermitian skin effect (NHSE) is extended from noninteracting systems to interacting many-body systems by studying an exactly solvable non-Hermitian model, the Lieb-Liniger Bose gas with imaginary vector potential. The NHSE is characterized quantitatively through solving the Bethe ansatz equations and calculating the model's density profiles and momentum distributions. It is found that the NHSE is enhanced for bound-state solutions on the attractive side, while it shows a nonmonotonic behavior for the scattering state. This work provides an example of NHSE in exactly solvable many-body systems and suggests its extension to other non-Hermitian many-body systems, particularly integrable models.
Article
Physics, Multidisciplinary
J. Settino, N. Lo Gullo, F. Plastina, A. Minguzzi
Summary: The study introduces a method to accurately evaluate the spectral function of a gas of one-dimensional bosons, showing three main singularity lines in the spectral function under lattice confinement, with the Lieb-II mode exhibiting divergence, providing a way to probe this mode in experiments with ultracold atoms.
PHYSICAL REVIEW LETTERS
(2021)
Article
Quantum Science & Technology
Thomas Fogarty, Thomas Busch
Summary: This study demonstrates that a quantum Otto cycle involving a transition of an ultracold gas between superfluid and insulating phases can outperform single particle cycles. Utilizing the energy gap and the interplay between lattice forces and particle distribution can lead to a many-body cooperative effect. Introducing an approximate shortcut to adiabaticity for efficient cycling around a critical point can help mitigate unwanted non-equilibrium dynamics.
QUANTUM SCIENCE AND TECHNOLOGY
(2021)
Article
Physics, Applied
Yajiang Hao, Yiwang Liu, Xiangguo Yin
Summary: In this study, the correlation properties of the ground state of Tonks-Girardeau gases are investigated in momentum space. The ground state wavefunction in coordinate space is obtained using the Bose-Fermi mapping method based on the wavefunction of spin-polarized fermions. Fourier transformation is then applied to obtain the ground state wavefunction, pair correlation, and reduced one-body density matrix in momentum space. The correlations in momentum space exhibit larger values only in small momentum regions and vanish in most other regions. Additionally, the lowest natural orbital and occupation distribution in momentum space are obtained.
INTERNATIONAL JOURNAL OF MODERN PHYSICS B
(2023)
Article
Physics, Multidisciplinary
Bjoern Schrinski, Anders S. Sorensen
Summary: Photons strongly coupled to material systems provide a new approach to realize nonlinear optics at the level of individual photons and study the dynamics of non-equilibrium quantum many-body systems. By using a simple physical polariton-picture, we can analytically describe the dynamics of photons coupled to a one-dimensional array of two-level atoms, including polariton scattering inside the medium and reflections of polaritons from the array's edge. We show that inelastic collisions, observed in small systems, also occur in infinite systems due to the existence of multiple bands in the dispersion relation. The developed theory serves as an effective field theory for studying nonlinear optics and many-body dynamics.
NEW JOURNAL OF PHYSICS
(2022)
Article
Chemistry, Physical
Verena A. Neufeld, Hong-Zhou Ye, Timothy C. Berkelbach
Summary: Metallic solids are an important class of materials that have not been extensively studied using wave function-based electronic structure theories. In this study, we used optimized Gaussian basis sets and coupled-cluster theory to investigate the structure of solid lithium and aluminum. Our results, which were compared to experimental values, showed accuracy comparable to common density functionals. Additionally, two approximate improvements to the coupled-cluster method were found to enhance the results.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Materials Science, Multidisciplinary
C. A. Perroni, G. De Filippis, V Cataudella
Summary: A different variational approach is proposed at zero temperature to study ground-state features of the Frohlich model including electron-electron and electron-phonon interactions. The electronic spectral function is calculated from weak to intermediate electron-phonon coupling regime, showing a transfer of spectral weight from the incoherent hump to the coherent peak. Three density regimes are identified: low densities with single large polaron characteristics, intermediate densities with a rapid crossover from incoherent to coherent dynamics, and high densities with a conventional metallic phase. The results are relevant for recent tunneling and photoemission experiments in SrTiO3-based systems.
Article
Physics, Multidisciplinary
Bei Xu, Zhongze Guo, Qiang Gu
Summary: The diagram technique is used to study the ground state properties of a generalized spin-3/2 Fermi gas, which shows that the spin-mixing term always strengthens the ground state energy and effective mass.
Article
Mathematics, Applied
Michele Correggi, Marco Falconi, Marco Olivieri
Summary: In this paper, we study the ground state energy and ground states of systems coupling nonrelativistic quantum particles and force-carrying Bose fields using the quasiclassical approximation. We prove that the ground state energy of the fully microscopic model converges to a nonlinear quasiclassical functional, which can be interpreted as the lowest energy of a Pekar-like functional with an effective nonlinear interaction for the particles only.
Article
Optics
Tobias Ilg, Hans Peter Buechler
Summary: We study the behavior of the excitation spectrum across the quantum phase transition from a superfluid to a supersolid phase of a dipolar Bose gas in one dimension. Using an effective Hamiltonian that includes beyond-mean-field effects, we analyze the system based on Bogoliubov theory with multiple order parameters. Our results show that the supersolid phase exhibits a stable excitation spectrum with Goldstone modes and an amplitude mode in the low-energy regime, and the transition into the supersolid phase is driven by the roton instability in a parameter regime achievable for dysprosium atoms.
Article
Optics
Kazuya Nishimura, Eiji Nakano, Kei Iida, Hiroyuki Tajima, Takahiko Miyakawa, Hiroyuki Yabu
Summary: This study investigates the properties of Fermi polarons formed by impurity atoms in ultracold atomic Fermi gases, showing that these properties exhibit spatial anisotropies reflecting the momentum anisotropy of the background dipolar Fermi gas. The effective mass and momentum drag parameter of the polaron both tend to decrease by approximately 10% as the DDI strength increases up to its critical value, while the longitudinal properties show weak dependence on the DDI.
Article
Optics
Min-Quan He, Dan-Bo Zhang, Z. D. Wang
Summary: This paper proposes a quantum Gaussian filter method and develops a hybrid quantum-classical algorithm feasible on near-term quantum computers. The method determines the coefficients of linear combination classically and optimizes them through postprocessing on classical computers, enabling more flexibility in filtering. Numerical simulations demonstrate the effectiveness of the method, and an alternative full quantum approach is also proposed.
Article
Chemistry, Physical
Justin Copenhaver, Adam Wasserman, Birgit Wehefritz-Kaufmann
Summary: This paper reviews two methods for finding the ground state of molecular Hamiltonians using Ising model-based quantum annealers and compares their relative effectiveness and resource requirements by calculating the properties of molecules. The study found that while these methods can accurately predict the ground state properties of small molecules, they are still outperformed by modern classical algorithms and face challenges in scaling resource requirements.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Energy & Fuels
Rabin Nepal, Hyeok Jin Kim, Jeeban Poudel, Sea Cheon Oh
Summary: Excessive use of fossil fuels has had a significant impact on global warming and the energy crisis, necessitating the promotion and development of alternative energy sources. Converting waste biomass into energy is important for solid waste management. This study improves the fuel properties of spent coffee grounds (SCG) through torrefaction and identifies the optimal conditions for this process.
Article
Multidisciplinary Sciences
Stasja Stanisic, Jan Lukas Bosse, Filippo Maria Gambetta, Raul A. Santos, Wojciech Mruczkiewicz, Thomas E. O'Brien, Eric Ostby, Ashley Montanaro
Summary: The authors successfully reproduced qualitative properties of the Fermi-Hubbard model using a VQE-based algorithm on a superconducting quantum processor, and employed various error-mitigation techniques to demonstrate the effectiveness of the algorithm.
NATURE COMMUNICATIONS
(2022)
Article
Optics
Muhammad S. Hasan, J. Polo, J. C. Pelayo, Th Busch
Summary: This study demonstrates that an accelerated atomic impurity in a spin-orbit coupled Bose-Einstein condensate undergoes oscillations in the supersolid stripe phase, similar to the phenomenon of Bloch oscillations in solids. The oscillations do not affect the periodicity of the matter wave lattice, but excite phonon modes within the supersolid. The decay of the oscillations is primarily caused by the dispersion of the wavepacket, but assuming the impurity to be a bright soliton can counteract this to a large extent.
JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS
(2022)
Article
Physics, Multidisciplinary
C. Campbell, J. Li, Th Busch, T. Fogarty
Summary: Supersymmetry allows for the construction of a hierarchy of Hamiltonians with common spectral properties and connected through super-potentials. The iso-spectral properties of these Hamiltonians connect the dynamics and control of different eigenstates through supersymmetric intertwining relations. In this work, we explore how this property enables the study of general dynamics, shortcuts to adiabaticity, and quantum speed limits for different states of distinct supersymmetric partner potentials using the infinite box as an example.
NEW JOURNAL OF PHYSICS
(2022)
Article
Quantum Science & Technology
Nathan Keenan, Niall F. Robertson, Tara Murphy, Sergiy Zhuk, John Goold
Summary: In this study, we digitally simulate the quantum dynamics of a spin-21 XXZ spin chain on a noisy near-term quantum device, and extract the high temperature transport exponent at the isotropic point. By simulating the temporal decay of the relevant spin correlation function using a pseudo-random state generated by a tailored random circuit on the ibmq-montreal 27 qubit device, we observe a spin excitation on a homogeneous background. The subsequent discrete time dynamics on the device reveal an anomalous super-diffusive exponent consistent with the conjectured Kardar-Parisi-Zhang (KPZ) scaling at the isotropic point. Furthermore, we restore spin diffusion by applying an integrability breaking potential.
NPJ QUANTUM INFORMATION
(2023)
Article
Optics
Jake Xuereb, Steve Campbell, John Goold, Andre Xuereb
Summary: We examine the deterministic quantum computation with one-clean-qubit model (DQC1) complexity class as an open quantum system. We show that the evolution of the logical qubit in any algorithm in the complexity class can be described as an open quantum system undergoing unital dynamics. Unital quantum channels respect the Tasaki-Crooks fluctuation theorem, which is captured by the thermodynamics of the logical qubit. As an application, we investigate the equilibrium and nonequilibrium thermodynamics of the DQC1 trace estimation algorithm, revealing the impact of computational inputs and logical qubit temperature on the algorithm's quality and fluctuations experienced.
Article
Optics
Jose Carlos Pelayo, Karol Gietka, Thomas Busch
Summary: In distributed quantum sensing, correlations between multiple modes of a photonic system are used to improve the precision of measuring an unknown parameter. This study investigates the metrological potential of a multimode, tilted Bose-Hubbard system and demonstrates that it can achieve parameter estimation at the Heisenberg limit. By optimizing the initial state, the limit can be reached without requiring correlations between different modes. Furthermore, strategies are proposed to obtain quadratic dependence on the number of modes in a more realistic experimental setup.
Article
Physics, Multidisciplinary
Mohamed Boubakour, Thomas Fogarty, Thomas Busch
Summary: We study a minimal quantum Otto heat engine with an interacting few-body system in a harmonic trap, where the interaction strength is considered as an additional tunable parameter during the work strokes. By calculating the figures of merit of the engine as a function of temperature, we clearly show in which parameter regimes the interactions assist in engine performance. We also compare the interaction-enhanced cycle with the case where the system remains scale-invariant, studying the finite-time dynamics and the subsequent tradeoff between efficiency and power.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Optics
Fam Le Kien, Sile Nic Chormaic, Thomas Busch
Summary: This study investigates the directional dependence of the coupling between a nanofiber-guided light field and a two-level atom with an electric quadrupole transition. It is found that the absolute value of the quadrupole Rabi frequency depends on the propagation direction of the light field in certain cases. The directional dependence of the coupling leads to directional dependence of spontaneous emission into guided modes. The study also reveals that the directional dependence of the atom-field coupling in the case of quadrupole transitions is not solely due to spin-orbit coupling of light, but also involves contributions from the gradient of the spatial phase factor of the field.
Article
Quantum Science & Technology
Archak Purkayastha, Giacomo Guarnieri, Steve Campbell, Javier Prior, John Goold
Summary: We introduce a unique class of cyclic quantum thermal machines (QTMs) that can maximize their performance at a finite cycle duration T where they are most irreversible. These QTMs can interpolate between standard collisional QTMs and autonomous QTMs operated by simultaneous coupling to multiple macroscopic baths. We discuss the physical realization of these processes and demonstrate that it requires a finite number of copies of the baths. The analysis also reveals interesting connections with Zeno and anti-Zeno effects.
Article
Physics, Fluids & Plasmas
Oisin Culhane, Mark T. Mitchison, John Goold
Summary: Recent experiments have shown the generation of coherent mechanical oscillations in a suspended carbon nanotube, similar to a lasing transition. In this study, we investigate this phenomenon from the perspective of work extraction, modeling a nanoelectromechanical device as a quantum flywheel or battery that converts electrical power into stored mechanical energy. By introducing a microscopic model that matches the experimental findings, we compute the Wigner function of the quantum vibrational mode in its nonequilibrium steady state. We utilize two approaches, ergotropy and nonequilibrium free energy, to characterize the threshold for self-sustained oscillations in nonequilibrium quantum thermodynamics. We find that ergotropy serves as an order parameter for the phonon lasing transition. The framework employed in this study can be generalized and applied to other mesoscopic quantum devices.
Article
Optics
Giacomo Guarnieri, Mark T. Mitchison, Archak Purkayastha, Dieter Jaksch, Berislav Buca, John Goold
Summary: Spontaneous periodic oscillation can emerge in the repeated-interaction description of open quantum systems, which is significant for implementing specific spin models in quantum simulators.
Article
Optics
Fam Le Kien, Sile Nic Chormaic, Thomas Busch
Summary: The optical force between two coupled parallel nanofibers was studied using the array mode theory. It was found that the forces of even array modes are attractive, while the forces of odd array modes are repulsive. The optical forces depend on the array mode type, fiber radius, light wavelength, and fiber separation distance.
Article
Optics
Fam Le Kien, Sile Nic Chormaic, Thomas Busch
Summary: In this study, we investigate the transfer of angular momentum from guided photons to a two-level atom through electric quadrupole transition near an optical nanofiber. We demonstrate that the axial orbital torque exerted by the driving guided field on the atom is determined by the selection rules for the quadrupole transition and the conservation law of angular momentum with photon angular momentum given by Minkowski formulation. We calculate the torques for the quadrupole transitions between specific sublevels of different hyperfine-structure levels in a Rb-87 atom.
Article
Physics, Multidisciplinary
Christopher Campbell, Thomas Fogarty, Thomas Busch
Summary: We study the dynamics of an ultracold quantum many-body system when quenching between two super-symmetric Hamiltonians. We show that the dynamics can be conveniently described using knowledge about the initial state only. In the case of a fermionic gas initially trapped in an infinite box potential, we observe many-body revivals when quenching to higher order supersymmetric partner potentials, with some revivals being robust at finite temperatures.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Materials Science, Multidisciplinary
Cecilia Chiaracane, Archak Purkayastha, Mark T. Mitchison, John Goold
Summary: Understanding and controlling quantum transport in low-dimensional systems is crucial for heat management at the nanoscale. This study investigates the effect of quasiperiodic disorder, which induces fractality in the energy spectrum, on the thermal and electric conductivities of a noninteracting model. The research finds that the presence of dephasing noise enhances transport in the subdiffusive regime and leads to multiple peaks in both thermal and electric conductivities, violating the Wiedemann-Franz law. This feature can be utilized to enhance the performance of quantum thermal machines.
Article
Optics
Mark T. Mitchison, Archak Purkayastha, Marlon Brenes, Alessandro Silva, John Goold
Summary: This study proposes a scheme to measure the temperature of pure states through quantum interference, showing that even individual pure quantum states can have temperatures in completely isolated quantum systems.
