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Quantum computers hold the potential to unlock new discoveries in complex quantum systems by enabling the simulation of physical systems that have heretofore been impossible to implement on classical computers due to intractability. A system of particular interest is that of dirty bosons, whose physics highlights the intriguing interplay of disorder and interactions in quantum systems, playing a central role in describing, for instance, ultracold gases in a random potential, doped quantum magnets, and amorphous superconductors. Here, we demonstrate how quantum computers can be used to elucidate the physics of dirty bosons in one and two dimensions. Specifically, we explore the disorder-induced delocalized-to-localized transition using adiabatic state preparation. In one dimension, the quantum circuits can be compressed to small enough depths for execution on currently available quantum computers. In two dimensions, the compression scheme is no longer applicable, thereby requiring the use of large-scale classical state vector simulations to emulate quantum computer performance. In addition, simulating interacting bosons via emulation of a noisy quantum computer allowed us to study the effect of quantum hardware noise on the physical properties of the simulated system. Our results suggest that scaling laws control how noise modifies observables versus its strength, the circuit depth, and the number of qubits. Moreover, we observe that noise impacts the delocalized and localized phases differently. A better understanding of how noise alters the observed properties of the simulated system is essential for leveraging near-term quantum devices for simulation of dirty bosons, and indeed for condensed matter systems in general.

Principal component analysis (PCA) is a widely used tool in machine learning algorithms, but it can be computationally expensive. In 2014, Lloyd, Mohseni & Rebentrost proposed a quantum PCA (qPCA) algorithm [Nat. Phys. 10, 631 (2014)] that has not yet been experimentally demonstrated due to challenges in preparing multiple quantum state copies and implementing quantum phase estimations. In this study, we presented a hardware-efficient approach for qPCA, utilizing an iterative approach that effectively resets the relevant qubits in a nuclear magnetic resonance (NMR) quantum processor. Additionally, we introduced a quantum scattering circuit that efficiently determines the eigenvalues and eigenvectors (principal components). As an important application of PCA, we focused on classifying thoracic CT images from COVID-19 patients and achieved high accuracy in image classification using the qPCA circuit implemented on the NMR system. Our experiment highlights the potential of near-term quantum devices to accelerate qPCA, opening up new avenues for practical applications of quantum machine learning algorithms. [ABSTRACT FROM AUTHOR]

The review article presents the recent progress in quantum computing and simulation within the field of biological sciences. The article is designed mainly into two portions: quantum computing and quantum simulation. In the first part, significant aspects of quantum computing was illustrated, such as quantum hardware, quantum RAM and big data, modern quantum processors, qubit, superposition effect in quantum computation, quantum interference, quantum entanglement, and quantum logic gates. Simultaneously, in the second part, vital features of the quantum simulation was illustrated, such as the quantum simulator, algorithms used in quantum simulations, and the use of quantum simulation in biological science. Finally, the review provides exceptional views to future researchers about different aspects of quantum simulation in biological science. [ABSTRACT FROM AUTHOR]

The interaction of light and matter at the single-photon level is of central importance in various fields of physics, including, e.g., condensed matter physics, astronomy, quantum optics, and quantum information. Amplification of such quantum light–matter interaction can be highly beneficial to, e.g., improve device performance, explore novel phenomena, and understand fundamental physics, and has therefore been a long-standing goal. Furthermore, simulation of light–matter interaction in the regime of ultrastrong coupling, where the interaction strength is comparable to the bare frequencies of the uncoupled systems, has also become a hot research topic, and considerable progress has been made both theoretically and experimentally in the past decade. In this review, we provide a detailed introduction of recent advances in amplification of quantum light–matter interaction and simulation of ultrastrong light–matter interaction, particularly in cavity and circuit quantum electrodynamics and in cavity optomechanics. [ABSTRACT FROM AUTHOR]

AB-stacked bilayer graphene has garnered significant scientific interest owing to its superior electron transport properties, even when compared to monolayer graphene; these superior properties are attributed to the additional π orbital overlaps in the x–y plane. In this study, the nearest-neighbour tight-binding (NNTB) model for AB-stacked bilayer graphene was developed. Using this NNTB approximation, a numerical analysis simulator using non-equilibrium Green's function (NEGF) equations to describe the quantum transport properties of electrons in the bilayer graphene lattice potential was developed using MATLAB. Based on these numerical analysis simulations, various metrics of interest such as the E-K dispersion relation, density of states (DOS), and transmission coefficients were obtained for each specified lattice width and length. Furthermore, the electronic transport properties of two variants of bilayer graphene—zigzag edge and armchair edge variants—were examined in these simulations. The dispersion relation of the zigzag edge variant exhibited no bandgap, whereas the armchair edge variant exhibited an alternating trend of semiconductor behaviour from the 3n − 1 and 3n series and metallic behaviour for the 3n + 1 series; this is consistent with contemporary research. Furthermore, the DOS simulations revealed the existence of a significant concentration of quantum states in the mid-band for the zigzag edge variant; by contrast, for the armchair edge variant, the number of states was the largest at the first quartile-band and the third quartile-band region. The transmission coefficients for both the zigzag and armchair edge variants featured similar distributions throughout the energy spectrum. However, for the zigzag edge variant, the coefficient was larger and the bandgap was tunable, with the bandgap at unity transmission ranging from 0 to 0.0484 eV or higher depending on the dimensions. These findings provide valuable insights into the electronic transport properties of bilayer graphene, highlighting its potential for advanced electronic applications. [ABSTRACT FROM AUTHOR]

Copyright of Micronanoelectronic Technology is the property of Micronanoelectronic Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rydberg atoms have highly controllable exotic properties such as strong interatomic interaction, high polarizability, and long lifetimes which enabled unprecedented progress in Rydberg atom-based quantum Technologies. We present a brief review of recent progress in the development of quantum technologies using Rydberg atoms. We highlight the recent advances in the various regimes of quantum technologies such as quantum Information processing, quantum sensing, quantum simulation of many-body physics and single-photon sources for quantum communications. [ABSTRACT FROM AUTHOR]

This work develops a quantum control application of many-body quantum chaos for ultracold bosonic gases trapped in optical lattices. It is long known how to harness exponential sensitivity to changes in initial conditions for control purposes in classically chaotic systems. In the technique known as targeting, instead of a hindrance to control, the instability becomes a resource. Recently, this classical targeting has been generalized to quantum systems either by periodically countering the inevitable quantum state spreading or by introducing a control Hamiltonian, where both enable localized states to be guided along special chaotic trajectories toward any of a broad variety of desired target states. Only strictly unitary dynamics are involved; i.e. it gives a coherent quantum targeting. In this paper, the introduction of a control Hamiltonian is applied to Bose–Hubbard systems in chaotic dynamical regimes. Properly selected unstable mean field solutions can be followed particularly rapidly to states possessing precise phase relationships and occupancies. In essence, the method generates a quantum simulation technique that can access rather special states. The protocol reduces to a time-dependent control of the chemical potentials, opening up the possibility for application in optical lattice experiments. Explicit applications to custom state preparation and stabilization of quantum many-body scars are presented in one- and two-dimensional lattices (three-dimensional applications are similarly possible). [ABSTRACT FROM AUTHOR]

Quantum simulation is capable of simulating certain dynamical systems in continuous time—Schrödinger's equations being the most direct and well known—more efficiently than classical simulation. Any linear dynamical system can in fact be transformed into a system of Schrödinger's equations via a method called Schrödingerisation (Jin et al. 2022. Quantum simulation of partial differential equations via Schrödingerisation. (https://arxiv.org/abs/2212.13969) and Jin et al. 2023. Phys. Rev. A108, 032603. (doi:10.1103/PhysRevA.108.032603)). We show how Schrödingerisation allows quantum simulation to be directly used for the simulation of continuous-time versions of general (explicit) iterative schemes or discrete linear dynamical systems. In particular, we use this new method to solve linear systems of equations and for estimating the maximum eigenvector and eigenvalue of a matrix, respectively. This method is applicable using either discrete-variable quantum systems or on hybrid continuous-variable and discrete-variable quantum systems. This framework provides an interesting alternative to solve linear algebra problems using quantum simulation. [ABSTRACT FROM AUTHOR]

Artificial 1D and 2D lattices have emerged as a powerful platform for the emulation of lattice Hamiltonians, the fundamental study of collective many‐body effects, and phenomena arising from non‐trivial topology. Exciton‐polaritons, bosonic part‐light and part‐matter quasiparticles, combine pronounced nonlinearities with the possibility of on‐chip implementation. In this context, organic semiconductors embedded in microcavities have proven to be versatile candidates to study nonlinear many‐body physics and bosonic condensation, and in contrast to most inorganic systems, they allow the use at ambient conditions since they host ultra‐stable Frenkel excitons. A well‐controlled, high‐quality optical lattice is implemented that accommodates light‐matter quasiparticles. The realized polariton graphene presents with excellent cavity quality factors, showing distinct signatures of Dirac cone and flatband dispersions as well as polariton lasing at room temperature. This is realized by filling coupled dielectric microcavities with the fluorescent protein mCherry. The emergence of a coherent polariton condensate at ambient conditions are demonstrated, taking advantage of coupling conditions as precise and controllable as in state‐of‐the‐art inorganic semiconductor‐based systems, without the limitations of e.g. lattice matching in epitaxial growth. This progress allows straightforward extension to more complex systems, such as the study of topological phenomena in 2D lattices including topological lasers and non‐Hermitian optics. [ABSTRACT FROM AUTHOR]

This article presents a new compressed representation of Boolean functions, called CFLOBDDs (for Context-Free-Language Ordered Binary Decision Diagrams). They are essentially a plug-compatible alternative to BDDs (Binary Decision Diagrams), and hence are useful for representing certain classes of functions, matrices, graphs, relations, and so forth in a highly compressed fashion. CFLOBDDs share many of the good properties of BDDs, but—in the best case—the CFLOBDD for a Boolean function can be exponentially smaller than any BDD for that function. Compared with the size of the decision tree for a function, a CFLOBDD—again, in the best case—can give a double-exponential reduction in size. They have the potential to permit applications to (i) execute much faster and (ii) handle much larger problem instances than has been possible heretofore. We applied CFLOBDDs in quantum-circuit simulation and found that for several standard problems, the improvement in scalability, compared to BDDs, is quite dramatic. With a 15-minute timeout, the number of qubits that CFLOBDDs can handle are 65,536 for Greenberger-Horne-Zellinger, 524,288 for Bernstein-Vazirani, 4,194,304 for Deutsch-Jozsa, and 4,096 for Grover's algorithm, besting BDDs by factors of 128×, 1,024×, 8,192×, and 128×, respectively. [ABSTRACT FROM AUTHOR]

This paper investigates the performance of vacuum gate dielectric doping-free carbon nanotube/nanoribbon field-effect transistors (VGD-DL CNT/GNRFETs) via computational analysis employing a quantum simulation approach. The methodology integrates the self-consistent solution of the Poisson solver with the mode space non-equilibrium Green's function (NEGF) in the ballistic limit. Adopting the vacuum gate dielectric (VGD) paradigm ensures radiation-hardened functionality while avoiding radiation-induced trapped charge mechanisms, while the doping-free paradigm facilitates fabrication flexibility by avoiding the realization of a sharp doping gradient in the nanoscale regime. Electrostatic doping of the nanodevices is achieved via source and drain doping gates. The simulations encompass MOSFET and tunnel FET (TFET) modes. The numerical investigation comprehensively examines potential distribution, transfer characteristics, subthreshold swing, leakage current, on-state current, current ratio, and scaling capability. Results demonstrate the robustness of vacuum nanodevices for high-performance, radiation-hardened switching applications. Furthermore, a proposal for extrinsic enhancement via doping gate voltage adjustment to optimize band diagrams and improve switching performance at ultra-scaled regimes is successfully presented. These findings underscore the potential of vacuum gate dielectric carbon-based nanotransistors for ultrascaled, high-performance, energy-efficient, and radiation-immune nanoelectronics. [ABSTRACT FROM AUTHOR]

Summary: Quantum computing resources are predominantly accessible through cloud services, with a potential future shift to edge networks. This paradigm and the increasing global interest in quantum computing have amplified the need for efficient, adaptable resource management strategies and service models for quantum systems. However, many limitations in the quantum resources' quantity, quality, availability, and cost pose significant challenges for conducting research in practical environments. To address these challenges, we proposed iQuantum, a holistic and lightweight discrete‐event simulation toolkit uniquely tailored to model hybrid quantum computing environments. We also present a detailed system model for prototyping and problem formulation in quantum resource management. Through rigorous empirical validation and evaluations using large‐scale quantum workload datasets, we demonstrate the flexibility and applicability of our toolkit in various use cases. iQuantum provides a versatile environment for designing and evaluating quantum resource management policies such as quantum task scheduling, backend selection, hybrid task offloading, and orchestration in the quantum cloud‐edge continuum. Our work endeavors to create substantial contributions to quantum computing modeling and simulation, empowering the creation of future resource management strategies and quantum computing's broader applications. [ABSTRACT FROM AUTHOR]

Boson sampling has been theoretically proposed and experimentally demonstrated to show quantum computational advantages. However, it still lacks the deep understanding of the practical applications of boson sampling. Here we propose that boson sampling can be used to efficiently simulate the work distribution of multiple identical bosons. We link the work distribution to boson sampling and numerically calculate the transition amplitude matrix between the single-boson eigenstates in a one-dimensional quantum piston system, and then map the matrix to a linear optical network of boson sampling. The work distribution can be efficiently simulated by the output probabilities of boson sampling using the method of the grouped probability estimation. The scheme requires at most a polynomial number of the samples and the optical elements. Our work opens up a new path towards the calculation of complex quantum work distribution using only photons and linear optics. [ABSTRACT FROM AUTHOR]

Discrete-time quantum walks with position-dependent coin operators have numerous applications. For a position dependence that is sufficiently smooth, it has been provided in Nzongani et al. (Quantum circuits for discrete-time quantum walks with position-dependent coin operator, arXiv:2211.05271, 2022) an approximate quantum-circuit implementation of the coin operator that is efficient. If we want the quantum-circuit implementation to be exact (e.g., either, in the case of a smooth position dependence, to have a perfect precision, or in order to treat a non-smooth position dependence), but the depth of the circuit not to scale exponentially, then we can use the linear-depth circuit of the previous reference, which achieves a depth that is linear at the cost of introducing an exponential number of ancillas. In this paper, we provide an adjustable-depth quantum circuit for the exact implementation of the position-dependent coin operator. The lower the depth of the circuit is, the more we have to add ancillary qubits, so this adjustable-depth circuit we propose is the right tool for a good adaptation to the experimental platform: one will typically reduce the depth as much as the experimental platform can handle the added ancillary qubits that go with the reduction of the depth. This adjustable-depth circuit consists in (i) applying in parallel, with a linear-depth circuit, only certain operator-packs of coin operators (rather than all of them as in the original linear-depth circuit), each pack contributing linearly to the depth, and in (ii) applying sequentially these packs, which contributes exponentially to the depth. Hence, given an input position state, one has to wait the right operator-pack to apply the coin operator to the coin state of this position. The key technical point of this work, which is the main technical novelty with respect to the previous reference, is that the one-hot encoding of the ancillary positions at the beginning of each operator-pack is selective, that is, we perform this encoding only for certain positions (those whose internal state we want to apply the coin operator to). [ABSTRACT FROM AUTHOR]

Quantum simulation qubit models of electronic Hamiltonians rely on specific transformations in order to take into account the fermionic permutation properties of electrons. These transformations (principally the Jordan–Wigner transformation (JWT) and the Bravyi–Kitaev transformation) correspond in a quantum circuit to the introduction of a supplementary circuit level. In order to include the fermionic properties in a more straightforward way in quantum computations, we propose to use methods issued from Geometric Algebra (GA), which, due to its commutation properties, are well adapted for fermionic systems. First, we apply the Witt basis method in GA to reformulate the JWT in this framework and use this formulation to express various quantum gates. We then rewrite the general one and two-electron Hamiltonian and use it for building a quantum simulation circuit for the Hydrogen molecule. Finally, the quantum Ising Hamiltonian, widely used in quantum simulation, is reformulated in this framework. [ABSTRACT FROM AUTHOR]

Long-range interactions are relevant for a large variety of quantum systems in quantum optics and condensed matter physics. In particular, the control of quantum–optical platforms promises to gain deep insights into quantum-critical properties induced by the long-range nature of interactions. From a theoretical perspective, long-range interactions are notoriously complicated to treat. Here, we give an overview of recent advancements to investigate quantum magnets with long-range interactions focusing on two techniques based on Monte Carlo integration. First, the method of perturbative continuous unitary transformations where classical Monte Carlo integration is applied within the embedding scheme of white graphs. This linked-cluster expansion allows extracting high-order series expansions of energies and observables in the thermodynamic limit. Second, stochastic series expansion quantum Monte Carlo integration enables calculations on large finite systems. Finite-size scaling can then be used to determine the physical properties of the infinite system. In recent years, both techniques have been applied successfully to one- and two-dimensional quantum magnets involving long-range Ising, XY, and Heisenberg interactions on various bipartite and non-bipartite lattices. Here, we summarise the obtained quantum-critical properties including critical exponents for all these systems in a coherent way. Further, we review how long-range interactions are used to study quantum phase transitions above the upper critical dimension and the scaling techniques to extract these quantum critical properties from the numerical calculations. [ABSTRACT FROM AUTHOR]

Rydberg atom arrays offer promising platforms for quantum simulation of correlated quantum matter and raise great interests. This work proposes a novel stripe‐lattice model with "Raman superarray of Rydberg atoms" to realize bosonic fractional quantum anomalous Hall (FQAH) phase. Two types of Rydberg states, arranged in a supperarray configuration and with Raman‐assisted dipole‐exchange couplings, are implemented to realize a minimal QAH model for hard‐core bosons populated into a topological flat band with large bulk gap under proper tunable experimental condition. With this the bosonic FQAH phase can be further achieved and probed feasibly. In particular, a novel quench protocol is proposed to probe the fractionalized excitations by measuring the correlated quench dynamics featured by fractional charge tunneling between bulk and chiral edge modes in the open boundary. [ABSTRACT FROM AUTHOR]

The most direct approach for characterizing the quantum dynamics of a strongly interacting system is to measure the time evolution of its full many-body state. Despite the conceptual simplicity of this approach, it quickly becomes intractable as the system size grows. An alternate approach is to think of the many-body dynamics as generating noise, which can be measured by the decoherence of a probe qubit. Here we investigate what the decoherence dynamics of such a probe tells us about the many-body system. In particular, we utilize optically addressable probe spins to experimentally characterize both static and dynamical properties of strongly interacting magnetic dipoles. Our experimental platform consists of two types of spin defects in nitrogen delta-doped diamond: nitrogen-vacancy colour centres, which we use as probe spins, and a many-body ensemble of substitutional nitrogen impurities. We demonstrate that the many-body system's dimensionality, dynamics and disorder are naturally encoded in the probe spins' decoherence profile. Furthermore, we obtain direct control over the spectral properties of the many-body system, with potential applications in quantum sensing and simulation.

ABSTRACTFock-state lattices (FSLs) consist of the Fock states of photons and atoms, establishing a quantum photonic platform for simulating condensed matter physics. Remarkably, various topological phenomena, such as topological edge states, strain-induced Landau levels, the valley Hall effect, and the quantum anomalous Hall effect, are intricately linked to the quantum properties of light. Recent advancements in state-of-the-art superconducting circuits have enabled the observation of these topological quantum photonic phenomena. With scalable dimensions and flexible structure engineering, FSLs offer a novel tool for investigating high-dimensional topological physics and devising innovative devices for quantum information processing. This review delves into the latest theoretical and experimental developments in this emerging field, situated at the intersection of quantum optics, topological physics, and quantum information.

We showcase the digital quantum simulation of the action of a Hamiltonian that governs the interaction between a quantum mechanical oscillator and an optical field, generating quantum entanglement between them via gravitational effects. This is achieved by making use of a boson-qubit mapping protocol and a digital gate decomposition that allow us to run the simulations in the quantum computers available in the IBM Quantum platform. We present the obtained results for the fidelity of the experiment in two different quantum computers, after applying error mitigation and post-selection techniques. The achieved results correspond to fidelities over 90%, which indicates that we were able to perform a faithful digital quantum simulation of the interaction and therefore of the generation of quantum entanglement by gravitational means in optomechanical systems. [ABSTRACT FROM AUTHOR]

Copyright of Advances in Biochemistry / Postepy Biochemii is the property of Polish Biochemical Society / Acta Biochimica Polonica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Display omitted] The realization of spin–orbit-coupled ultracold gases has driven a wide range of research and is typically based on the rotating wave approximation (RWA). By neglecting the counter-rotating terms, RWA characterizes a single near-resonant spin–orbit (SO) coupling in a two-level system. Here, we propose and experimentally realize a new scheme for achieving a pair of two-dimensional (2D) SO couplings for ultracold fermions beyond RWA. This work not only realizes the first anomalous Floquet topological Fermi gas beyond RWA, but also significantly improves the lifetime of the 2D-SO-coupled Fermi gas. Based on pump–probe quench measurements, we observe a deterministic phase relation between two sets of SO couplings, which is characteristic of our beyond-RWA scheme and enables the two SO couplings to be simultaneously tuned to the optimum 2D configurations. We observe intriguing band topology by measuring two-ring band-inversion surfaces, quantitatively consistent with a Floquet topological Fermi gas in the regime of high Chern numbers. Our study can open an avenue to explore exotic SO physics and anomalous topological states based on long-lived SO-coupled ultracold fermions. [ABSTRACT FROM AUTHOR]

Molecular nanomagnets (MNMs), molecules containing interacting spins, have been a playground for quantum mechanics. They are characterized by many accessible low-energy levels that can be exploited to store and process quantum information. This naturally opens the possibility of using them as qudits, thus enlarging the tools of quantum logic with respect to qubit-based architectures. These additional degrees of freedom recently prompted the proposal for encoding qubits with embedded quantum error correction (QEC) in single molecules. QEC is the holy grail of quantum computing and this qudit approach could circumvent the large overhead of physical qubits typical of standard multi-qubit codes. Another important strength of the molecular approach is the extremely high degree of control achieved in preparing complex supramolecular structures where individual qudits are linked preserving their individual properties and coherence. This is particularly relevant for building quantum simulators, controllable systems able to mimic the dynamics of other quantum objects. The use of MNMs for quantum information processing is a rapidly evolving field which still requires to be fully experimentally explored. The key issues to be settled are related to scaling up the number of qudits/qubits and their individual addressing. Several promising possibilities are being intensively explored, ranging from the use of single-molecule transistors or superconducting devices to optical readout techniques. Moreover, new tools from chemistry could be also at hand, like the chiral-induced spin selectivity. In this paper, we will review the present status of this interdisciplinary research field, discuss the open challenges and envisioned solution paths which could finally unleash the very large potential of molecular spins for quantum technologies. [ABSTRACT FROM AUTHOR]

In this study, a novel technique for the quantum splitting of multi-qubit gates is presented. This brings innumerable advantages for the analysis of quantum circuits, the design of simulators, and back-ends, which are fundamentally needed in quantum computing development environments. This technique can be applied to any gate that involves two or more qubits, facilitating its treatment during its application in configurations of the Greenberger-Horne-Zeilinger (GHZ) type for more than two entangled photons, or protocols where CNOT or Toffoli gates connect qubits that are not close, which implies the intensive use of SWAP gates. The study is completed with the application of the new technique to quantum teleportation, quantum secret sharing, and entanglement swapping. [ABSTRACT FROM AUTHOR]

Quantum algorithms for simulating quantum systems provide a clear and provable advantage over classical algorithms in fault-tolerant settings. There is also interest in quantum algorithms and their implementation in Noisy Intermediate Scale Quantum (NISQ) settings. In these settings, various noise sources and errors must be accounted for when executing any experiments. Recently, NISQ devices have been verified as versatile testbeds for simulating open quantum systems and have been used to simulate simple quantum channels. Our goal is to solve the more complicated problem of simulating convex mixtures of single qubit Pauli channels on NISQ devices. We consider two specific cases: mixtures of Markovian channels that result in a non-Markovian channel (M + M = nM) and mixtures of non-Markovian channels that result in a Markovian channel (nM + nM = M). For the first case, we consider mixtures of Markovian single qubit Pauli channels; for the second case, we consider mixtures of Non-Markovian single qubit depolarising channels, which is a special case of the single qubit Pauli channel. We show that efficient circuits, which account for the topology of currently available devices and current levels of decoherence, can be constructed by heuristic approaches that reduce the number of CNOT gates used in our circuit. We also present a strategy for regularising the process matrix so that the process tomography yields a completely positive and trace-preserving (CPTP) channel. Key points This work simulates the convex mixtures of single qubit Markovian and non-Markovian quantum channels on NISQ devices provided by the IMBQE. The circuits used to implement the channels take into account the topolgy of the quantum device used as well as the number of CNOT gates used. We present a strategy for regularising the process matrix to ensure the quantum process tomography yields a CPTP channel. Something that is not correctly implemented in Qiskit. A method is outlined for finding mixtures of non-Markovian depolarising channels that yield a Markovian depolarising channel. It is also shown that, one cannot convexly mix two Markovian depolarising channels that leads to a non-Markovian depolarising channel. [ABSTRACT FROM AUTHOR]

Rydberg atoms have highly controllable exotic properties such as strong inter-atomic interaction, high polarizability, and long lifetimes which enabled unprecedented progress in Rydberg atom-based quantum Technologies. We present a brief review of recent progress in the development of quantum technologies using Rydberg atoms. We highlight the recent advances in the various regimes of quantum technologies such as quantum Information processing, quantum sensing, quantum simulation of many-body physics and single-photon sources for quantum communications.

Multislice method is widely used to simulate the elastic interaction of an electron beam with matter in electron microscopy. In this paper, we propose a quantum algorithm of multislice method. With the use of quantum circuit this quantum version of multislice method costs less storage space and less runtime than the classical algorithm by taking advantage of the feature of quantum computing. We have used a classical supercomputer to simulate a quantum circuit, and successfully carried out the quantum multislice computation and obtained the expected result on a virtual quantum circuit, which proves the feasibility and correctness of the quantum algorithm. This work demonstrates the potential application prospect of quantum computing to the research of computational physics as a good example.

Abstract Artificial 1D and 2D lattices have emerged as a powerful platform for the emulation of lattice Hamiltonians, the fundamental study of collective many‐body effects, and phenomena arising from non‐trivial topology. Exciton‐polaritons, bosonic part‐light and part‐matter quasiparticles, combine pronounced nonlinearities with the possibility of on‐chip implementation. In this context, organic semiconductors embedded in microcavities have proven to be versatile candidates to study nonlinear many‐body physics and bosonic condensation, and in contrast to most inorganic systems, they allow the use at ambient conditions since they host ultra‐stable Frenkel excitons. A well‐controlled, high‐quality optical lattice is implemented that accommodates light‐matter quasiparticles. The realized polariton graphene presents with excellent cavity quality factors, showing distinct signatures of Dirac cone and flatband dispersions as well as polariton lasing at room temperature. This is realized by filling coupled dielectric microcavities with the fluorescent protein mCherry. The emergence of a coherent polariton condensate at ambient conditions are demonstrated, taking advantage of coupling conditions as precise and controllable as in state‐of‐the‐art inorganic semiconductor‐based systems, without the limitations of e.g. lattice matching in epitaxial growth. This progress allows straightforward extension to more complex systems, such as the study of topological phenomena in 2D lattices including topological lasers and non‐Hermitian optics.

Here we present a superadiabatic scheme on a quantum computer to quickly prepare the ground state of the Agassi model, a typical quadrupole plus pairing model with broad applications in nuclear physics as well as many-body systems. By virtue of the Floquet-engineering counterdiabatic driving, this method can accelerate the conventional quantum adiabatic driving without extra control fields. Compared to the adiabatic protocol, the resulting scheme allows for a drastic increase in the final fidelity within a short evolution time, which can effectively inhibit the decoherence effects in quantum simulators. Numerical simulations demonstrate the feasibility of this proposal for fast generating the ground state of Agassi model with different sites. This research opens an avenue for future quantum simulations, and provides a useful method to address currently unanswered questions in nuclear physics using intermediate-scale quantum coprocessors.

Electrical DNA sequencing has attracted significant attention in recent years due to its simplified sequencing protocol, compact sequencing system, and relatively low sequencing cost. In the design and fabrication of the sequencing device, carbon-based nanomaterials such as graphene have been explored as a promising sensing material that provides an excellent combination of spatial resolution and base specificity. Using first-principles simulation, we determined the effect on the electrical conductivity of a one-dimensional carbon chain due to the presence of four DNA bases. The simulation results indicate that the interaction between the carbon chain and different DNA bases leads to different levels of conductivity change in the carbon chain. Quantitatively, base A is the most difficult base to detect due to its relatively small current change. Furthermore, the results also show that the relative orientation of the bases with respect to the carbon chain can affect the induced current change in the chain. This information can be used to optimize the structural design of future sequencing devices. Collectively, the first-principles simulation results suggest the integration of a one-dimensional carbon chain with supporting nanofluidic designs can provide a viable approach towards the development of a compact, robust, and high-resolution DNA sequencing system.

Advances in quantum simulator technology are increasingly required because research on quantum algorithms is becoming more sophisticated and complex. State vector simulation utilizes CPU and memory resources in computing nodes exponentially with respect to the number of qubits; furthermore, in a variational quantum algorithm, the large number of repeated runs by classical optimization is also a heavy load. This problem has been addressed by preparing numerous computing nodes or simulation frameworks that operate effectively. This study aimed to accelerate quantum simulation using two newly proposed methods: to efficiently utilize limited computational resources by adjusting the ratio of the MPI and distributed processing parallelism corresponding to the target problem settings and to slim down the Hamiltonian by considering the effect of accuracy on the calculation result. Ground-state energy calculations of a fermionic model were performed using a variational quantum eigensolver (VQE) on an HPC cluster with up to 1024 FUJITSU Processor A64FX connected to each other by InfiniBand; the processor is also used on supercomputer Fugaku. We achieved 200 times higher speed over VQE simulations and demonstrated 32 qubits ground-state energy calculations in acceptable time. This result indicates that > 30 qubit state vector simulations can be realistically utilized for further research on variational quantum algorithms.

Non-Hermitian systems satisfying parity-time (PT) symmetry have aroused considerable interest owing to their exotic features. Anti-PT symmetry is an important counterpart of the PT symmetry, and has been studied in various classical systems. Although a Hamiltonian with anti-PT symmetry only differs from its PT-symmetric counterpart in a global ±i phase, the information and energy exchange between systems and environment are different under them. It is also suggested theoretically that anti-PT symmetry is a useful concept in the context of quantum information storage with qubits coupled to a bosonic bath. So far, the observation of anti-PT symmetry in individual quantum systems remains elusive. Here, we implement an anti-PT-symmetric Hamiltonian of a single qubit in a single trapped ion by a designed microwave and optical control-pulse sequence. We characterize the anti-PTphase transition by mapping out the eigenvalues at different ratios between coupling strengths and dissipation rates. The full information of the quantum state is also obtained by quantum state tomography. Our work allows quantum simulation of genuine open-system feature of an anti-PT-symmetric system, which paves the way for utilizing non-Hermitian properties for quantum information processing.

Summary: This study presents a quantum secret sharing (QSS) protocol designed using Grover's search algorithm in a noisy environment. The proposed protocol utilizes Grover's three‐particle quantum state. The proposed scheme is divided into secret information sharing and eavesdropping checking. The dealer prepares an encoded state by encoding the classical information as a marked state and shares the states' qubits between three participants. Using the amplitude‐damping noise and the phase‐damping noise as conventional noisy channels, it can be demonstrated that secret information can be conveyed between participants with some information lost. The security analysis shows the scheme is stringent against malicious participants or eavesdroppers. The simulation analysis is done on the cloud platform IBM‐QE thereby showing the practical feasibility of the scheme. Finally, an application of the proposed scheme is demonstrated in visual cryptography using the GNEQR representation of images. [ABSTRACT FROM AUTHOR]

In this paper, a new junctionless graphene nanoribbon tunnel field-effect transistor (JLGNR TFET) is proposed as a multi-gas nanosensor. The nanosensor has been computationally assessed using a quantum simulation based on the self-consistent solutions of the mode space non-equilibrium Green's function (NEGF) formalism coupled with the Poisson's equation considering ballistic transport conditions. The proposed multi-gas nanosensor is endowed with two top gates ensuring both reservoirs' doping and multi-gas sensing. The investigations have included the IDS-VGS transfer characteristics, the gas-induced electrostatic modulations, subthreshold swing, and sensitivity. The order of change in drain current has been considered as a sensitivity metric. The underlying physics of the proposed JLGNR TFET-based multi-gas nanosensor has also been studied through the analysis of the band diagrams behavior and the energy-position-resolved current spectrum. It has been found that the gas-induced work function modulation of the source (drain) gate affects the n-type (p-type) conduction branch by modulating the band-to-band tunneling (BTBT) while the p-type (n-type) conduction branch still unaffected forming a kind of high selectivity from operating regime point of view. The high sensitivity has been recorded in subthermionic subthreshold swing (SS < 60 mV/dec) regime considering small gas-induced gate work function modulation. In addition, advanced simulations have been performed for the detection of two different types of gases separately and simultaneously, where high-performance has been recorded in terms of sensitivity, selectivity, and electrical behavior. The proposed detection approach, which is viable, innovative, simple, and efficient, can be applied using other types of junctionless tunneling field-effect transistors with emerging channel nanomaterials such as the transition metal dichalcogenides materials. The proposed JLGNRTFET-based multi-gas nanosensor is not limited to two specific gases but can also detect other gases by employing appropriate gate materials in terms of selectivity. [ABSTRACT FROM AUTHOR]

A quantum Pauli noise is a nonunitary process that alters the state of a qubit by random application of the four Pauli operators. We investigate a four-qubit quantum circuit, consisting of a pipeline of three independently controlled Pauli gates, for simulating the general class of qubit Pauli noises. The circuit with a fixed architecture is controllable by three separable quantum states from three auxiliary qubits in order to adjust the parameters of the targeted Pauli noise on the principal qubit. Important Pauli noises such as bit flip, phase flip, bit phase flip, and depolarizing noise are readily simulated, along with an infinite subset of other Pauli noises. However, the quantum circuit with its simple and fixed architecture cannot simulate all conceivable Pauli noises, and a characterization is proposed, in the parameter space of the Pauli noises, denoting those that are simulable by the circuit and those that are not. The circuit is a useful tool to contribute to controlled simulation, on current or future quantum processors, of nonunitary processes of noise and decoherence. [ABSTRACT FROM AUTHOR]

Recent theoretical and algorithmic developments have improved the accuracy with which path integral dynamics methods can include nuclear quantum effects in simulations of condensed-phase vibrational spectra. Such methods are now understood to be approximations to the delocalized classical Matsubara dynamics of smooth Feynman paths, which dominate the dynamics of systems such as liquid water at room temperature. Focusing mainly on simulations of liquid water and hexagonal ice, we explain how the recently developed quasicentroid molecular dynamics (QCMD), fast-QCMD, and temperature-elevated path integral coarse-graining simulations (Te PIGS) methods generate classical dynamics on potentials of mean force obtained by averaging over quantum thermal fluctuations. These new methods give very close agreement with one another, and the Te PIGS method has recently yielded excellent agreement with experimentally measured vibrational spectra for liquid water, ice, and the liquid-air interface. We also discuss the limitations of such methods. [ABSTRACT FROM AUTHOR]

Quantum simulation provides a computationally feasible approach to model and study many problems in chemistry, condensed-matter physics, or high-energy physics where quantum phenomenon defines the systems behavior. In high-energy physics, quite a few possible applications are investigated in the context of gauge theories and their application to dynamic problems, topological problems, high-baryon density configurations, or collective neutrino oscillations. In particular, schemes for simulating neutrino oscillations are proposed using a quantum walk framework. In this study, we approach the problem of simulating neutrino oscillation from the perspective of open quantum systems by treating the position space of quantum walk as environment. We have obtained the recurrence relation for Kraus operator which is used to represent the dynamics of the neutrino flavor change in the form of reduced coin states. We establish a connection between the dynamics of reduced coin state and neutrino phenomenology, enabling one to fix the simulation parameters for a given neutrino experiment and reduces the need for extended position space to simulate neutrino oscillations. We have also studied the behavior of linear entropy as a measure of entanglement between different flavors in the same framework. [ABSTRACT FROM AUTHOR]

Due to the inevitable existence of quantum effects, a classical description generically breaks down after a finite quantum break‐time tq$t_q$. We aim to find criteria for determining tq$t_q$. To this end, we construct a new prototype model that features numerous dynamically accessible quantum modes. Using explicit numerical time evolution, we establish how tq$t_q$ depends on the parameters of the system such as its particle number N. The presence of a classical instability leads to tq∼lnN$t_q\sim \ln N$ or tq∼N$t_q\sim \sqrt {N}$. In the stable case, we observe tq∼N$t_q\sim N$, although full quantum breaking may not take place at all. We find that the different regimes merge smoothly with tq∼Nγ$t_q\sim N^\gamma$ (0<γ<1$0<\gamma <1$). As an outlook, we point out possibilities for transferring our results to black holes and expanding spacetimes. [ABSTRACT FROM AUTHOR]

Arrays of individual atoms trapped in optical microtraps with micrometer‐scale sizes have emerged as a fundamental, versatile, and powerful platform for quantum sciences and technologies. This platform enables the bottom‐up engineering of quantum systems, offering the capability of low‐entropy preparation of quantum states with flexible geometry, as well as manipulation and detection at the single‐site level. The utilization of ultracold itinerant atoms with tunnel coupling in optical microtraps provides new opportunities for quantum simulation, enabling the exploration of exotic quantum states, phases, and dynamics, which would otherwise be challenging to achieve in conventional optical lattices due to high entropy and limited geometric flexibility. Here, the development of tunnel‐coupled optical microtraps for the manipulation of ultracold atomic quantum systems and its recent advances are briefly reviewed. [ABSTRACT FROM AUTHOR]

Motivated by recent realizations of two-dimensional (2D) superconducting-qubit lattices, we propose a protocol to simulate Hofstadter butterfly with synthetic gauge fields in superconducting circuits. Based on the existing 2D superconducting-qubit lattices, we construct a generalized Hofstadter model on zigzag lattices, which has a fractal energy spectrum similar to the original Hofstadter butterfly. By periodically modulating the resonant frequencies of qubits, we engineer a synthetic gauge field to mimic the generalized Hofstadter Hamiltonian. A spectroscopic method is used to demonstrate the Hofstadter butterfly from the time evolutions of experimental observables. We numerically simulate the dynamics of the system with realistic parameters, and the results show a butterfly spectrum clearly. Our proposal provides a promising way to realize the Hofstadter butterfly on the latest 2D superconducting-qubit lattices and will stimulate the quantum simulation of novel properties induced by magnetic fields in superconducting circuits. [ABSTRACT FROM AUTHOR]

Originating from the Hamiltonian of a single qubit system, the phenomenon of the avoided level crossing is ubiquitous in multiple branches of physics, including the Landau–Zener transition in atomic, molecular, and optical physics, the band structure of condensed matter physics and the dispersion relation of relativistic quantum physics. We revisit this fundamental phenomenon in the simple example of a spinless relativistic quantum particle traveling in (1+1)-dimensional space-time and establish its relation to a spin-1/2 system evolving under a PT -symmetric Hamiltonian. This relation allows us to simulate 1-dimensional eigenvalue problems with a single qubit. Generalizing this relation to the eigenenergy problem of a bulk system with N spatial dimensions reveals that its eigenvalue problem can be mapped onto the time evolution of the edge state with (N − 1) spatial dimensions governed by a non-Hermitian Hamiltonian. In other words, the bulk eigenenergy state is encoded in the edge state as a hologram, which can be decoded by the propagation of the edge state in the temporal dimension. We argue that the evolution will be PT -symmetric as long as the bulk system admits parity symmetry. Our work finds the application of PT -symmetric and non-Hermitian physics in quantum simulation and provides insights into the fundamental symmetries. [ABSTRACT FROM AUTHOR]