Quantum Preprints

In this paper, we present an interpolation scheme for FRQI images based on bilinear interpolation. To accomplish this, we formulated several quantum modules, i.e., assignment module, increment module, and quarter module, and suffused them into our proposed quantum image interpolation circuit. The concrete quantum circuits to accomplish up-scaling and down-scaling... Read more
Published on: 2020-10-21
The second quantum revolution has been built on a foundation of fundamental research at the intersection of physics and information science, giving rise to the discipline we now call Quantum Information Science (QIS). The quest for new knowledge and understanding drove the development of new experimental tools and rigorous theory,... Read more
Published on: 2020-10-21
Quantum entanglement is a fundamental property of coherent quantum states and an essential resource for quantum computing. While two-qubit entanglement has been demonstrated for spins in silicon, creation of multipartite entanglement, a first step toward implementing quantum error correction, has remained challenging due to the difficulties in controlling a multi-qubit... Read more
Published on: 2020-10-21
We consider the fate of $1/N$ expansions when a many-body quantum system is quenched across criticality and show the emergence of ${rm e}^{2lambda t}/N$ as renormalized parameter ruling the quantum-classical transition and accounting non-perturbatively for the local divergence rate $lambda$ of mean-field solutions. In terms of ${rm e}^{2lambda t}/N$, quasiclassical... Read more
Published on: 2020-10-21
Recently, Tsai et al. (Laser Phys. Lett. 17, 075202, 2020) proposed a lightweight authenticated semi-quantum key distribution protocol for a quantum participant to share a secret key with a classical participant. However, this study points out that an attacker can use a modification attack to make both participants share a... Read more
Published on: 2020-10-21
These are the lecture notes used in the course Understanding Quantum Chemistry for 1st year master chemistry at the Vrije Universiteit Amsterdam. The schedule is 2 weeks on HF and 2 weeks on DFT, which provides a quite rough ride for the the students. The lecture notes also include exercises.... Read more
Published on: 2020-10-21
Non-Hermitian systems can produce branch singularities known as exceptional points (EPs). The topological properties of an EP can involve either the winding of eigenvalues that produces a discriminant number (DN) or the eigenvector holonomy that generates a Berry phase, making them richer than typical degenerate points in Hermitian systems. However,... Read more
Published on: 2020-10-21
Quantum engineering using photonic structures offer new capabilities for atom-photon interactions for quantum optics and atomic physics, which could eventually lead to integrated quantum devices. Despite the rapid progress in the variety of structures, coherent excitation of the motional states of atoms in a photonic waveguide using guided modes has... Read more
Published on: 2020-10-21
Quantum error mitigation techniques are at the heart of quantum computation. Conventional quantum error correction codes are promising solutions, while they become infeasible in the noisy intermediate scale quantum (NISQ) era, hurdled by the required expensive resources. The variational quantum learning scheme (VQLS), which is composed of trainable quantum circuits... Read more
Published on: 2020-10-21
Controlling and narrowing x-ray frequency spectra in magnetically perturbed two-target nuclear forward scattering is theoretically studied. Our system is composed of two $^{57}$FeBO$_3$ crystals applied with external magnetic fields and illuminated by broadband x-ray synchrotron radiation pulses of 14.4 keV central photon energy. Combinations of switching individual magnetic field lead... Read more
Published on: 2020-10-21
Diamond nitrogen-vacancy (NV) center magnetometry has recently received considerable interest from researchers in the fields of applied physics and sensors. The purpose of this review is to analyze the principle, sensitivity, technical development potential, and application prospect of the diamond NV center magnetometry. This review briefly introduces the physical characteristics... Read more
Published on: 2020-10-21
For the identification of non-trivial quantum phase, we exploit a Bell-type correlation that is applied to the one-dimensional spin-1 XXZ chain. It is found that our generalization of bipartite Bell correlation can take a decomposed form of transverse spin correlation together with high-order terms. The formulation of density-matrix renormalisation group... Read more
Published on: 2020-10-21
The correspondence principle is a cornerstone in the entire construction of quantum mechanics. This principle has been recently challenged by the observation of an early-time exponential increase of the out-of-time-ordered correlator (OTOC) in classically non-chaotic systems [E.B. Rozenbaum et al., Phys. Rev. Lett. 125, 014101 (2020)], Here we show that... Read more
Published on: 2020-10-21
Recently, Li et al. (Int J Theor Phys: DOI: 10.1007/s10773-020-04588-w, 2020) proposed a multiparty quantum key agreement protocol via non-maximally entangled cluster states. They claimed that the proposed protocol can help all the involved participants have equal influence on the final shared key. However, this study points out a loophole... Read more
Published on: 2020-10-21
Quantum state verification provides an efficient approach to characterize the reliability of quantum devices for generating certain target states. The figure of merit of a specific strategy is the estimated infidelity $epsilon$ of the tested state to the target state, given a certain number of performed measurements n. Entangled measurements... Read more
Published on: 2020-10-21
We experimentally study the emergence of high-energy equilibrium states in a chiral vortex gas of like-circulation vortices realized within a disk-shaped atomic Bose-Einstein condensate. In contrast to the familiar triangular Abrikosov lattice, the lowest-energy state of the superfluid in a rotating frame, we observe the formation of rotating vortex equilibria... Read more
Published on: 2020-10-21
An analytical solution for a quantum wave impedance in a case of piesewise constant potential was derived. It is in fact an analytical depiction of a well-known iterative method of a quantum wave impedance determination. The expression for a transmission probability as a function of a particle energy for an... Read more
Published on: 2020-10-21
The Dyson series is an infinite sum of multi-dimensional time-ordered integrals, which serves as a formal representation of the quantum time evolution operator in the interaction picture. Using the mathematical tool of divided differences, we introduce an alternative representation for the series that is entirely free from both time ordering... Read more
Published on: 2020-10-21
We present an alternative method for describing the evolution of a mode of the quantized electromagnetic field in contact with a finite temperature thermal bath. We use the expansion of the field density operator in terms of coherent states and the related Glauber-Sudarshan $P$-function in phase space. The method allows... Read more
Published on: 2020-10-21
Strong nonlinear coupling of superconducting qubits and/or photons is a critical building block for quantum information processing. Due to the perturbative nature of the Josephson nonlinearity, linear coupling is often used in the dispersive regime to approximate nonlinear coupling. However, this dispersive coupling is weak and the underlying linear coupling... Read more
Published on: 2020-10-21