Quantum Properties Research Articles

Electronic-grade epitaxial (111) KTaO3 heterostructures.

KTaO3 heterostructures have recently attracted attention as model systems to study the interplay of quantum paraelectricity, spin-orbit coupling, and superconductivity. However, the high and low vapor pressures of potassium and tantalum present processing challenges to creating heterostructure interfaces clean enough to reveal the intrinsic quantum properties. Here, we report superconducting heterostructures based on high-quality epitaxial (111) KTaO3 thin films using an adsorption-controlled hybrid PLD to overcome the vapor pressure mismatch. Electrical and structural characterizations reveal that the higher-quality heterostructure interface between amorphous LaAlO3 and KTaO3 thin films supports a two-dimensional electron gas with substantially higher electron mobility, superconducting transition temperature, and critical current density than that in bulk single-crystal KTaO3-based heterostructures. Our hybrid approach may enable epitaxial growth of other alkali metal-based oxides that lie beyond the capabilities of conventional methods.

Precisely determining photon-number in real time

Superconducting transition-edge sensors (TES) are extremely sensitive microcalorimeters used as photon detectors with unparalleled energy resolution. They have found application from measuring astronomical spectra through to determining the quantum property of photon-number, n^=a^†a^, for energies from 0.6-2.33eV. However, achieving optimal energy resolution requires considerable data acquisition – on the order of 1GB/min – followed by post-processing, which does not allow access to energy information in real time. Here we use a custom hardware processor to process TES pulses while new detections are still being registered, allowing photon-number to be measured in real time as well as reducing data requirements by orders-of-magnitude. We resolve photon number up to n=16 – achieving up to parts-per-billion discrimination for low photon numbers on the fly – providing transformational capacity for applications of TES detectors from astronomy through to quantum technology.

Low Temperature (Down to 6 K) and Quantum Transport Characteristics of Stacked Nanosheet Transistors with a High-K/Metal Gate-Last Process.

Silicon qubits based on specific SOI FinFETs and nanowire (NW) transistors have demonstrated promising quantum properties and the potential application of advanced Si CMOS devices for future quantum computing. In this paper, for the first time, the quantum transport characteristics for the next-generation transistor structure of a stack nanosheet (NS) FET and the innovative structure of a fishbone FET are explored. Clear structures are observed by TEM, and their low-temperature characteristics are also measured down to 6 K. Consistent with theoretical predictions, greatly enhanced switching behavior characterized by the reduction of off-state leakage current by one order of magnitude at 6 K and a linear decrease in the threshold voltage with decreasing temperature is observed. A quantum ballistic transport, particularly notable at shorter gate lengths and lower temperatures, is also observed, as well as an additional bias of about 1.3 mV at zero bias due to the asymmetric barrier. Additionally, fishbone FETs, produced by the incomplete nanosheet release in NSFETs, exhibit similar electrical characteristics but with degraded quantum transport due to additional SiGe channels. These can be improved by adjusting the ratio of the channel cross-sectional areas to match the dielectric constants.

The Defects Genome of Janus Transition Metal Dichalcogenides.

2D Janus Transition Metal Dichalcogenides (TMDs) have attracted much interest due to their exciting quantum properties arising from their unique two-faced structure, broken-mirror symmetry, and consequent colossal polarization field within the monolayer. While efforts are made to achieve high-quality Janus monolayers, the existing methods rely on highly energetic processes that introduce unwanted grain-boundary and point defects with still unexplored effects on the material's structural and excitonic properties Through high-resolution scanning transmission electron microscopy (HRSTEM), density functional theory (DFT), and optical spectroscopy measurements; this work introduces the most encountered and energetically stable point defects. It establishes their impact on the material's optical properties. HRSTEM studies show that the most energetically stable point defects are single (VS and VSe) and double chalcogen vacancy (VS -VSe), interstitial defects (Mi), and metal impurities (MW) and establish their structural characteristics. DFT further establishes their formation energies and related localized bands within the forbidden band. Cryogenic excitonic studies on h-BN-encapsulated Janus monolayers offer a clear correlation between these structural defects and observed emission features, which closely align with the results of the theory. The overall results introduce the defect genome of Janus TMDs as an essential guideline for assessing their structural quality and device properties.

Study of shear Alfve’n waves with Landau quantization effect in degenerate relativistic plasma

In a ground breaking endeavor, we investigate a fundamental quantum property of fermions, specifically electrons, within a non-uniform quantized magnetic field, unveiling novel insights into shear Alfve’n waves in the relativistic realm of quantum plasma, particularly within the context of a degenerate Fermi gas. Employing the quantum magnetohydrodynamic model, we delve into the profound implications of the Landau quantization effect. This quantum phenomenon holds paramount importance across diverse fields such as condensed matter physics, astrophysics, and quantum information. Our study focuses on a plasma composed of degenerate relativistic electrons coexisting with cold fluid ions, which are non-degenerate particles. The findings of this research reveal substantial modifications in the thermodynamic, kinetic, and dispersion relation characteristics of shear Alfve’n waves when subjected to a non-uniform quantized magnetic field. This exploration offers a pioneering perspective on the intricate interplay between quantum physics and plasma dynamics, with implications for a wide array of scientific disciplines.

Bounds to electron spin qubit variability for scalable CMOS architectures

Spins of electrons in silicon MOS quantum dots combine exquisite quantum properties and scalable fabrication. In the age of quantum technology, however, the metrics that crowned Si/SiO2 as the microelectronics standard need to be reassessed with respect to their impact upon qubit performance. We chart spin qubit variability due to the unavoidable atomic-scale roughness of the Si/SiO2 interface, compiling experiments across 12 devices, and develop theoretical tools to analyse these results. Atomistic tight binding and path integral Monte Carlo methods are adapted to describe fluctuations in devices with millions of atoms by directly analysing their wavefunctions and electron paths instead of their energy spectra. We correlate the effect of roughness with the variability in qubit position, deformation, valley splitting, valley phase, spin-orbit coupling and exchange coupling. These variabilities are found to be bounded, and they lie within the tolerances for scalable architectures for quantum computing as long as robust control methods are incorporated.

Robust biometric identity authentication scheme using quantum voice encryption and quantum secure direct communications for cybersecurity

A significant problem facing cybersecurity is that most client/server identity authentication schemes depend on computational complexity which is recently challenged by the super exponential computational abilities of quantum computers. Quantum cryptography with its quantum mechanics principles solves this problem and provides mathematically un-hackable secure communication for the quantum computers epoch. Biometric authentication has a big challenge related to its protection as it has to be submitted and stored in encrypted form. Unfortunately, most existing biometric cryptosystems rely on classical cryptography, so they are insecure in quantum era. This problem is solved in this paper by introducing a novel three-factor biometric quantum identity authentication scheme combining something you know (password), something you produce (client’s voice), and something you are (client’s face image) is proposed. The scheme consists of two phases: client enrollment and client login/authentication. The methodology is to use in the enrollment phase, two layers of quantum encryption for the client’s voice signal. Each layer consists of two simple quantum circuits of SWAP and C-NOT quantum gates respectively using a different pseudorandom key obtained from a cellular automata (CA) pseudorandom generator. The proposed scheme has many merits. Firstly, it introduces a new design of muti-factors quantum biometric authentication scheme as the biometric voice data is processed, transmitted, and stored at the server database in an encrypted unconditionally secure quantum form which provides parallel processing, real-time communications, inherent level of security against attacks, tamper-proof security and exponential powerful storage capability due to the quantum properties. Secondly, the proposed scheme achieves double-layers security by combing quantum voice encryption and quantum secure direct communication in one process such that the quantum channel eavesdropper cannot obtain any valuable information in case of information leakage. Thirdly, the distribution and management of encryption key problem is solved as there is no need for key exchange prior to communication. Fourthly, it achieves high communication efficiency as although it is a three-factor biometric identity authentication, only one biometric data is sent in quantum encrypted form to the server. Fifthly, the numerical simulations showed that the proposed scheme has large key space, high key sensitivity and more robust performance against different types of attacks compared to other existing classical and quantum voice encryption schemes. Finally, as an identity authentication method, the proposed scheme achieves identification accuracy of 100% with zero False Rejection Rate (FRR) and zero False acceptance rate (FAR) which is perfect.

Quantum Convolutional Neural Networks for Line Orientation Classification in Pixelated Images

Quantum Convolutional Neural Networks (QCNNs) offer a promising avenue for image classification tasks due to their potential to leverage quantum properties for enhanced computational capabilities. In this paper, we explore the application of QCNNs for line orientation classification in pixelated images. Specifically, we investigate the differentiation between horizontal and vertical lines, a fundamental task in image processing and computer vision. We propose a QCNN architecture tailored to this task, leveraging quantum convolutional layers to extract features from pixelated images and classify line orientations. We demonstrate the effectiveness of our approach through experimental evaluation on benchmark datasets, comparing the performance of QCNNs with different optimizers. Our study integrated the QCNN operator and optimizer into Qiskit Machine Learning’s Neural Network Classifier, leveraging quantum computing techniques for classification tasks. Our QCNN model demonstrated a training accuracy of 71.43% and a test accuracy of 60.0%. Noteworthy observations include the failure of the SPSA optimizer to converge within the designated iterations, requiring twice the iterations compared to the COBYLA optimizer for convergence.

QTA Gitterchip Technology: Relationship Between Individual User Observations and Experimental Preclinical Data

Subjective evaluations, such as individual observations and anecdotal evidence, can provide valuable insights into the effectiveness and impact of devices providing beneficial health effects. In the present study the relationship between subjective user oberservations and controlled preclinical laboratory research was examined in detail for the beneficial health effects of devices using the QTA Gitterchip technology. The term "QTA" stands for "Quantum Tunneling Accelerator". Both devices of the present evaluation, QiOne® 2 Pro and QiBracelet®, aim to influence biological systems by affecting the quantum properties of water. This was achieved particularly through the modification of electron and proton tunneling processes. A total of 171 individually posted user observations were evaluated in detail. No formal questionnaire was used; users posted their subjective observations voluntarily and independently on social media forums. The corresponding experimental preclinical data were based on our publications during the last two years with cell culture techniques. The most predominant user observations were more calmless and serenity as well as a deeper and more relaxing sleep. This was reported in 20% of the user observations. In addition, about 17% of the users reported more energy and vitality and a better well-being and attitude of life. The other beneficial individual observations were below 10% such as an increased regeneration, more mind power and less pain and illness. Most of the user observations are related to a reduction of environmental oxidative stress, which is confirmed by the preclinical experimental studies, which were conducted independently during a period of two years. In conclusion, the present user observations and experimental investigations have shown that the QTA Gitterchip technology has a positive impact on cells by increasing their resistance against environmental stressors resulting in a positive impact on the human body. Thus, the use of the QTA Gitterchip technology improves and maintains well-being and health as well as the attitude of life

Interatomic Potential For Carbon Based Quantum‐Technology Applications

AbstractTo optimize parameters for laser processing of quantum‐technology relevant materials, such as diamond, precise atomistic simulations of the light‐matter interaction on large scales (on the order of atoms) are essential. Classical empirical interatomic potentials are commonly employed for simulating such a large number of atoms, however they fail to accurately capture all relevant effects of light‐matter interaction. Conversely, ab initio methods like Density Functional Theory (DFT) can effectively incorporate quantum properties arising from photon excitations, but their applicability is limited to small systems containing at most approximately atoms. Consequently, bridging the gap between achieving DFT precision and handling millions of atoms necessitates the development of innovative classes of interatomic potentials. In this paper, the construction of a highly accurate interatomic potential for diamond is presented, derived from an extensive dataset of DFT calculations. The parameters of the interatomic potential depend on the electronic temperature (). The findings demonstrate that this newly developed interatomic potential can aptly describe the laser processing of diamond for nanophotonic applications, achieving accuracy comparable to ab initio methods for large systems.

Custom Bell inequalities from formal sums of squares

Bell inequalities play a key role in certifying quantum properties for device-independent quantum information protocols. It is still a major challenge, however, to devise Bell inequalities tailored for an arbitrary given quantum state. Existing approaches based on sums of squares provide results in this direction, but they are restricted by the necessity of first choosing measurement settings suited to the state. Here, we show how the sum of square property can be enforced for an arbitrary target state by making an appropriate choice of nullifiers, which is made possible by leaving freedom in the choice of measurement. Using our method, we construct simple Bell inequalities for several families of quantum states, including partially entangled multipartite GHZ states and qutrit states. In most cases we are able to prove that the constructed Bell inequalities achieve self-testing of the target state. We also use the freedom in the choice of measurement to self-test partially entangled two-qubit states with a family of settings with two parameters. Finally, we show that some statistics can be self-tested with distinct Bell inequalities, hence obtaining new insight on the shape of the set of quantum correlations.

Traversable wormholes from Loop Quantum Gravity

This study introduces and investigates Lorentzian traversable wormhole solutions rooted in Loop Quantum Gravity (LQG). The static and spherically symmetric solutions to be examined stem from the energy density sourcing self-dual regular black holes discovered by L. Modesto, relying on the parameters associated with LQG, which account for the quantum nature of spacetime. We specifically focus on macroscopic wormholes characterized by small values of these parameters. Our analysis encompasses zero-tidal solutions and those with non-constant redshift functions, exploring immersion diagrams, curvatures, energy conditions, equilibrium requirements, and the requisite quantity of exotic matter to sustain these wormholes. The investigation underscores the influence of LQG parameters on these features, highlighting the pivotal role of spacetime's quantum properties in shaping such objects and governing their behavior.

Pd(II), Pt(II), Zn(II), Cd(II) and Hg(II) complexes of the newly prepared 1,2-benzo- isothiazol-3(2H)-dithiocarbamate (BIT-DTC) ligand

In the current work, we report the synthesis and characterization of new dithiocarbamate complexes derived from 1,2-benzoisothiazol-3(2H)-one (BitH). The ligand was synthesized by treating the BitH with carbon disulfide in a basic solution. The NMR technique confirmed the preparation of the ligand. The treatment of the Bit-dtcNa with the metal salt’s solution afforded the complexes of the type [M(Bit-dtc)2]; M = Zn, Cd, Hg, Pd, and Pt. The complexes were characterized via FT-IR and 1H-NMR techniques. The Zn, Pd, and Pt complexes were investigated theoretically, and some of their quantum properties were determined. These parameters include HOMO-LUMO energies, electron affinity, ionization potential, chemical hardness, dipole moment and the total energies of the optimized structures. Moreover, the surface structure of Zn and Hg complexes were investigated by SEM and XRD techniques. The SEM pattern showed a cubic structures for the Zn complex while the Hg complex appeared as a nano rods structure. The calculated average particle sizes for Zn and Hg complexes were 23 and 26 nm, respectively. KEY WORDS: Dithiocarbamate, 1,2-Benzoisothiazol-3(2H)-one, DFT, SEM, XRD Bull. Chem. Soc. Ethiop. 2024, 38(3), 889-899. DOI: https://dx.doi.org/10.4314/bcse.v38i4.6

Method to deterministically generate large-amplitude optical cat states

Cat states, as an important resource in the study of macroscopic quantum superposition and quantum information applications, have garnered widespread attention. To date, preparing large-sized optical cat states has remained challenging. We demonstrate that, by utilizing interaction-free measurement and the quantum Zeno effect, even a fragile quantum microscopic system can deterministically control and become entangled with strong light fields, thereby generating large-amplitude optical cat states. During the entire preparation process, our method ensures that the microscopic system functions within a weak field environment, so that its quantum property can be protected. Furthermore, we show that the preparation of cat states is possible even when the quantum microsystem suffers from significant photon loss, provided that optical losses from classical devices are kept low, which implies that the fidelity of the cat state can be enhanced by improvements to and the perfection of the classical optical system.

Axiomatic quasi-classical quantization of particle motion in the dissipative media

A self-consistent quasi-classical generalization of the axiomatic quantization of the translational motion of a particle in a dissipative medium is proposed, which is modeled by a drag force Fd , which depends in a power-law manner on the velocity v : Fd∼vn , where n is an arbitrary real number. A detailed analysis of the quasi-classical coherent state is carried out. It is shown that under condition n<3 the dissipative medium suppresses the quantum properties of particle motion, performing the function of a classical measuring device. Otherwise, there is no suppression of quantum properties.

High-fidelity entanglement routing in quantum networks

Quantum networks, endowed with their distinct quantum properties, are poised to emerge as indispensable platforms for the implementation of quantum information technology applications in the near future. Within the realm of quantum networks, the transmission of remote quantum information presents a pivotal and intricate challenge, commonly referred to as the entanglement routing problem. While previous efforts have delved into the intricacies of entanglement routing, there has been a notable oversight concerning the crucial parameter of entanglement fidelity. Hence, this paper introduces a novel Purification-enabled Entanglement Routing Algorithm (PERA). Initially, PERA utilizes the network throughput as the routing metric and ensures fidelity guarantees on all nodes in the link through a hop-by-hop purification process. Subsequently, acknowledging the probabilistic nature of entanglement purification, a strategy involving multiple attempts at purification is employed. Finally, a comprehensive utility function is deployed to address the path selection problem for multiple source–destination pairs. Numerical simulations confirm that PERA establishes entanglement connections with outstanding fidelity guarantees. Concurrently, PERA outperforms the baseline algorithm in terms of network throughput and resource utilization.

Automatic Detection of Nuclear Spins at Arbitrary Magnetic Fields via Signal-to-Image AI Model.

Quantum sensors leverage matter's quantum properties to enable measurements with unprecedented spatial and spectral resolution. Among these sensors, those utilizing nitrogen-vacancy (NV) centers in diamond offer the distinct advantage of operating at room temperature. Nevertheless, signals received from NV centers are often complex, making interpretation challenging. This is especially relevant in low magnetic field scenarios, where standard approximations for modeling the system fail. Additionally, NV signals feature a prominent noise component. In this Letter, we present a signal-to-image deep learning model capable of automatically inferring the number of nuclear spins surrounding a NV sensor and the hyperfine couplings between the sensor and the nuclear spins. Our model is trained to operate effectively across various magnetic field scenarios, requires no prior knowledge of the involved nuclei, and is designed to handle noisy signals, leading to fast characterization of nuclear environments in real experimental conditions. With detailed numerical simulations, we test the performance of our model in scenarios involving varying numbers of nuclei, achieving an average error of less than 2kHz in the estimated hyperfine constants.

Distinct Quantum States in Topological Insulator Surfaces of Nanowires and Nanoribbons of Bismuth Selenide (Bi2Se3)

AbstractTopological insulators (TIs) exhibit unconventional quantum phases that can be tuned by external quantum confinements. The geometry of the surface of 3D TIs plays a crucial role. For example, the geometrical crossover from 2D surfaces to a 1D cylinder results in a novel state with a Spin‐Berry Phase (SBP). Surface‐Enhanced Raman Scattering (SERS) with a sub‐micron spatial resolution is utilized to study the quantum‐confinement effects of quasi‐relativistic electrons along the perimeter of the circular bismuth selenide (Bi2Se3) nanowires. The presence of diameter‐dependent SERS in nanowires can be attributed to the self‐interference effect of the electronic wave‐function along the circumferential direction of the TI nanowires. Nanoribbons with rectangular cross‐section do not show this effect. Further gold nanoparticles are applied as plasmonic SERS sensors attached to the distinct topological surface states to manipulate quasi‐relativistic surface states of nanoribbons and nanowires. This technique enables to discriminate between different geometries of TI surface states and also opens a novel pathway to probe the quantum properties of topological surface states.

Enhanced Estimation of Quantum Properties with Common Randomized Measurements

Enhanced Estimation of Quantum Properties with Common Randomized Measurements

Quasi-classical theory of cyclotron resonance with accounting for dissipation

Based on the quasi-classical version of the canonical Caldirola–Kanai quantization, non-relativistic cyclotron resonance in a dissipative medium is studied. The corresponding particle propagator in the coordinate representation is found. It is shown that the combined effect of dissipation and a constant magnetic field reduces to the suppression of the quantum properties of a charged particle. In turn, a time-varying electric field that causes cyclotron resonance does not exhibit similar properties and does not affect the uncertainties of the particle coordinates.