Quantum Computing

This cover image, related to article number 2300457 by Selçuk Çakmak and co-workers, illustrates the layers of a soft-core processor to execute RISC (reduced instruction set computer)-V instruction set architecture (RISC-V assembly code) on a quantum processing unit (QPU) based on superconducting qubits. The soft-core processor circuit layer represents a quantum circuit that realizes the example code on the QPU. As a result, the quantum computer (QC) writes the message on the QC terminal screen.

Brownian Motion

The statistics of the position of an optically-trapped colloid immersed in a bacterial bath is prominently non-Gaussian. Costantino Di Bello, Rita Majumdar, Édgar Roldán, and coworkers (article number 2300427) develop an exactly-solvable theory for the fluctuations of a colloid in a diluted bacterial bath and explore its thermodynamic consequences. Fruits of their theory, they establish how can experimentalists infer the statistics of the forces exerted by the bacteria (often unaccessible experimentally) from the non-Gaussian features of the statistics of the colloid's position.

Anomalies are the violation of classical symmetries due to quantum effects. New methods have recently allowed to establish their non-renormalization in a number of cases, at a non-perturbative level and in presence of a lattice. The issue is relevant in several problems ranging from the anomaly-free construction of chiral lattice gauge theory under the anomaly cancellation condition to the universality properties observed in transport coefficients in condensed matter systems like Graphene, Hall insulators, or Weyl semimetals.

In this research, a quantum arithmetic logic unit based on quantum Fourier transform is proposed, capable of performing arithmetic ADD and logic NAND gate operations on N-inputs, with each input consisting of n-bit numbers. The paper also discusses the possible construction of a soft-core processor for the desired instruction set architecture, such as RISC-V, on the quantum processing unit.

In this work, the fluctuating, nonequilibrium dynamics of an optically-trapped Brownian particle within a dilute solution of active particles is studied. Authors propose a stochastic model in which the particle moves in a harmonic potential and experiences both thermal and Poisson shot-noise kicks with specified amplitude distribution due to moving active particles in the bath. A variety of exact analytical results for the particle position statistics are derived, together with a compact inference scheme with potential applications in soft-matter experiments. The article also sheds light on when and how to use the notion of effective temperature in such active systems.

In this paper, a new type of structured electron beam is introduced, which is the electron Airy tornado wave (eATW) with the characteristics of abrupt auto-focusing and rotation property in free space and in a longitudinal uniform magnetic field. It is also found that the eATWs propagate periodically in a magnetic field, and their patterns of intensity distributions show the time-like axial symmetry about a half-period point in a period of time.

Electronic density, spin polarization, as well as orbital and spin magnetizations of square periodic arrays of quantum dots or antidots subjected to the influence of a far-infrared cavity photon field are obtained using quantum electrodynamical density functional theory adapted to a 2D electron gas in a transverse homogeneous magnetic field.

A scheme to teleport an unknown superposition of two distinct momentum states of a neutral atom onto the similar momentum states of a distant atom at the receiving end through the off-resonant atomic Bragg diffraction. To teleport this unknown state from the sender to the receiver, we utilize an entangled link between these ends.

One often assumes that one can completely measure classical systems without altering them. In real scenarios, however, this may not always be possible: measuring the position of a small particle can randomly change its momentum and subsequent evolution. Here, the exact conditions are derived, which characterize when a statistics can be simulated classically, but assuming invasive measurements. It is shown that not all quantum experiments can be simulated in such a way.

Topological properties of photonic crystals or insulators are generally addressed by means of integer numbers obtained, for example, through the Berry connection. A completely different approach is proposed here : a 1D structure can be characterized by means of the poles and zeros of a function. The approach applies to non-Hermitian as well as disordered structures.

This paper presents the magnon–photon blockade effect within a hybrid optomagnomechanical system. It combines optics, magnetics, and mechanics to study how the interaction between magnons and photons can be controlled. The focus lies on investigating magnon squeezing under weak pump driving conditions and analyzing the second-order correlation function of the optomagnomechanical system, which could have implications for various applications in quantum information processing and computing.

A new scheme utilizing a cascade of four Mach–Zehnder modulators (MZMs) to generate a 32-fold millimeter wave is proposed. In this paper, the working principle and simulation experiments of this scheme are analyzed, and the optical sideband suppression ratios (OSSR) and RF sideband suppression ratios (RFSSR) are obtained to be 59.96, 60.02, 53.94, and 56.34, respectively.

The research aims to study a hybrid quantum-classical system in which a qubit as a quantum system coupled to a semi-infinite one-dimensional (1D) photonic crystal (PC) waveguide, and is controlled by a classical driving field. Here, the main purpose of the study is to assess the impact of coherent control on the dynamics of quantum Fisher information (QFI) and geometric phase (GP).

In this paper, the collective particle emission from a Bose-Einstein condensate in a 1D lattice is studied in detail. With time-periodic modulations of the interparticle interactions, the distinctly intermittent rather than conventionally continuous jets are observed. The decay of the trapped particles exhibits a stepwise structure, and a larger drive gives rise to a more significant intermittency.

Inspired by the successful synthesis of single-layer CoCl$$_2$$, it predicts that Janus single-layer CoClBr is a 2D intrinsic ferromagnetic semiconductor with a direct bandgap of 3.71 eV, a MAE of 542.25 $$\mu$$eV per Co atom, and a Curie temperature of 89.49 K. The magnetic properties can be regulated by biaxial strain. The MAE of Janus single-layer CoClBr reaches 1560.49 $$\mu$$eV per Co atom at a tensile strain of 5%.

This paper explores the impact of the generalized uncertainty principle on black hole solutions with spherical dark matter distributions. It examines the parameter $$\gamma$$ and its influence on supermassive black holes like Sgr. A* and M87*, utilizing data from the Event Horizon telescope. The study reveals unique deviations in event horizon and shadow radii, providing bounds on $$\gamma$$ at the $$3\sigma$$ confidence level. These findings have implications for laboratory experiments and astrophysical observations, reshaping the understanding of black holes.

The article analyzes universal quantum teleportation in memory or memory-less dynamics using partial collapse measurement operators. This study examines different noise models of physical significance with distinct Markovian and non-Markovian regions. The study shows that weak measurements and memory or non-Markovianity, can lead to universal quantum teleportation.