Classical Quantum Mechanics Research Articles

Performance advantage of discriminating one-versus-two incoherent sources based on quantum hypothesis testing

Performance advantage of discriminating one-versus-two incoherent sources based on quantum hypothesis testing

Local certification of unitary operations

In this work, we analyze the local certification of unitary quantum channels, which is a natural extension of quantum hypothesis testing. A particular case of a quantum channel operating on two systems corresponding to product states at the input, is considered. The goal is to minimize the probability of the type II error, given a specified maximum probability of the type I error, considering assistance through entanglement with auxiliary systems. Our result indicates connection of the local certification problem with a product numerical range of unitary matrices. We show that the optimal local strategy does not need usage of auxiliary systems and requires only single round of one-way classical communication. Moreover, we compare local and global certification strategies and show that typically local strategies are optimal, yet in some extremal cases, where global strategies make no errors, local ones may fail miserably. Finally, some application for local certification of von Neumann measurements are discussed as well.

Performance advantage of quantum hypothesis testing for partially coherent optical sources

Determining the presence of a potential optical source in the interest region is important for an imaging system and can be achieved by using hypothesis testing. The previous studies assume that the potential source is completely incoherent. In this paper, this problem is generalized to the scenario with partially coherent sources and any prior probabilities. We consider quantum-optimal error probability and a classical benchmark of two scenarios depending on the number of available temporal modes M. For M=1, we calculate the quantum Helstrom bound and the error probability of prior-based direct decision. For M≫1, we analyze the quantum Chernoff bound as well as the Chernoff bound of intensity-based direct imaging. In addition, we propose binary spatial-mode demultiplexing and the result demonstrates asymptotically optimal detection performance. Our findings may shed new light on super-resolution imaging in partially coherent scenarios.

Direct-bonded diamond membranes for heterogeneous quantum and electronic technologies

Diamond has superlative material properties for a broad range of quantum and electronic technologies. However, heteroepitaxial growth of single crystal diamond remains limited, impeding integration and evolution of diamond-based technologies. Here, we directly bond single-crystal diamond membranes to a wide variety of materials including silicon, fused silica, sapphire, thermal oxide, and lithium niobate. Our bonding process combines customized membrane synthesis, transfer, and dry surface functionalization, allowing for minimal contamination while providing pathways for near unity yield and scalability. We generate bonded crystalline membranes with thickness as low as 10 nm, sub-nm interfacial regions, and nanometer-scale thickness variability over 200 by 200 μm2 areas. We measure spin coherence times T2 for nitrogen vacancy centers in 150 nm-thick bonded membranes of up to 623 ± 21 μs, suitable for advanced quantum applications. We demonstrate multiple methods for integrating high quality factor nanophotonic cavities with the diamond heterostructures, highlighting the platform versatility in quantum photonic applications. Furthermore, we show that our ultra-thin diamond membranes are compatible with total internal reflection fluorescence (TIRF) microscopy, which enables interfacing coherent diamond quantum sensors with living cells while rejecting unwanted background luminescence. The processes demonstrated herein provide a full toolkit to synthesize heterogeneous diamond-based hybrid systems for quantum and electronic technologies.

Entropic uncertainty and quantum non-classicality of Unruh-Dewitt detectors in relativity

An object moving with the acceleration will change the temperature of environment around it, because of the presence of the Unruh thermal effect. In this work, we investigate the impact of Unruh thermal noise on the quantum-memory-assisted entropic uncertainty and quantum correlation regarding a pair of Unruh-Dewitt detectors. Specifically, we examine how the acceleration, the coupling strength between the external field and the detector, and the initial state affect the uncertainty and the system's quantum discord. It turns out that the Unruh effect will result in the loss of the systemic quantumness and inflation of the uncertainty. Moreover, it is revealed that the uncertainty is reversely correlated with the system's quantum discord. Thereby, it is believed that our investigations provide new insights into understanding the behavior of objects in the relativistic background.

Miscegenation and militarization: undoing racial colonial citizenship for the next century

ABSTRACT This essay considers the Immigration Act of 1924, otherwise known as the Johnson-Reed Act (JRA), within historical and contemporary contexts of anti-miscegenation and Indigenous erasure that are undercurrents of citizenship and immigration processes. By using a framework of settler colonialism carried out by the U.S. nation-state, we explore connections among racialized peoples in U.S. American empire and the push for racial purity through systems of blood quantum and anti-miscegenation laws. With attention to how colonialism from the continental USA flows to locales such as Guåhan/Guam, a place enacting sovereignty despite occupation and colonial possession, we consider how immigration and citizenship are wielded as tools of U.S. American militarization. Ultimately, we argue that critiquing miscegenation and militarism is necessary to overcome racial and colonial violences of empire.

ON THE NATURE OF TIME AND ITS VARIOUS PHYSICAL THEORIES PERCEPTION

Time is one of the most important and mysterious concepts for mankind. It plays an important role in the lives of each of us, it is widely used in many scientific fields, especially in physics and philosophy, but there are many questions about its true nature. This article discusses the perception of time in physical theories and its basic concepts, and compares the concepts of time in classical mechanics, relativity theory, and quantum mechanics. Specific characteristics of time in each theory and its influence on physical processes are considered. It also discusses the nature of time, its disappearance, and theoretical disagreements. The study brings together the philosophical and scientific aspects of the concept of time, offering a new perspective for those interested in learning.

Birds of passage: Rudolf Peierls and Dick Dalitz in Oxford

Abstract This paper traces the different routes that Rudolf Peierls and Dick Dalitz travelled on their way to being the founding members of a new Department of Theoretical Physics in Oxford. Peierls had had the good fortune to meet all of the originators of modern quantum mechanics in Europe and had been able to apply the new theory to many areas of physics. At Birmingham with Otto Frisch he wrote the famous Frisch-Peierls Memorandum which showed that it was possible to develop an atomic bomb. Dalitz had a shorter route to Oxford and worked with Peierls at Birmingham and Hans Bethe at Cornell before rejoining Peierls in Oxford after seven years in Chicago. His pioneering work on both the τ-θ puzzle and on the constituent quark model are then briefly described. The efforts of both Rudolf and Genia Peierls to create a ‘Bohr extended family’ model for his department in both Birmingham and Oxford are described, along with some observations about their style of theoretical physics research as ‘phenomenologists’.

Shallow-depth variational quantum hypothesis testing

Shallow-depth variational quantum hypothesis testing

Uniportal Laser-Assisted Video-Assisted Thoracoscopy (U-LA-VATS) for Lung Metastasectomy: Technical Description, Peri-Operative Results and Pertinent Literature Review.

Pulmonary metastasectomy (PM) is a well-established treatment that is able to contribute to the cure of oligometastatic cancer. Surgery should adopt the most lung-sparing approach possible to preserve pulmonary function (and, consequently, the quality of life) and to spare the lung for potential additional lung resections. In this framework, laser technology has been introduced in recent decades, but only few experiences combining laser technology with VATS approaches have been reported till now. The main focus of this manuscript is to report our institutional experience in performing lung-sparing laser-assisted PM by uniportal VATS (uniportal laser-assisted VATS: U-LA-VATS). The surgical technique and peri-operative results from our series of patients were herein presented and compared with the pertinent literature. Methods: Between March 2021 and November 2023, among 98 patients who underwent PM, a total of 24 patients (18 men (75%); 6 women (25%); mean age 61.4 years; age range 13-83 years) were treated with laser-assisted PM at our institution. Patients who underwent anatomical resection were excluded for the purpose of the analysis. The U-LA-VATS procedure adopted a modified laser-assisted lung resection technique for performing PM via VATS. Dedicated instruments are used, characterized by a long shape and a curved shape, with distal and proximal articulations. A surgical laser system (Thulium + Diodo OUTPUT 30-10 W, Quanta System S.p.a., Solbiate Olona, Italy) was used, and a 550-μm sterile optical fibre conducted through a specific thoracoscopic handpiece was introduced in the lowest part of the incision. Peri-operative results were analysed in all cohort and compared according to the surgical technique. Moreover, these results were compared with those reported in the literature. Comprehensive research of the literature was conducted on PubMed from 2000 to 2024. A review was performed and reported in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Results: In 12 cases (50%), thulium laser-assisted resection was performed using uniportal video-assisted thoracic surgery (VATS), and in the other cases (12, 50%), a (mini)thoracotomy access was adopted. In the thoracotomy group, the mean duration of surgery was 95 ± 57.7 min; meanwhile, it was 73.5 ± 35.5 in the uniportal VATS group. At the univariate analysis, this difference resulted to be statistically significant (p value 0.025). We did not observe intra-operative complications or remarkable malfunction of the laser system. We also did not report major complications after surgery; also the air-leak rate was 8.3% and 0% after thoracotomic and VATS procedures, respectively. Surgical margins were free from disease in all cases. Major and minor post-op complication rates were similar in both groups. The mean hospitalization after surgery was 2.9 ± 0.3 days for the uniportal VATS group and 3.7 ± 0.9 days for the thoracotomy group, this difference being statistically significant at the univariate analysis (p value = 0.015). Conclusions: U-LA-VATS is a safe and effective procedure, able to combine a parenchymal sparing exeresis with a mini-invasive approach. This procedure is associated with a shorter hospital stay compared with PM performed by a thoracotomic approach. Compared with the selected works for the review, our series is the only one describing the use of laser resection combined with a uniportal VATS approach.

Molecular modelling of luciferyl adenylate deprotonation in the active site of Photinus pyralis luciferase

Firefly bioluminescence is a product of chemical reactions that involve luciferin chromophore oxidation in the active site of luciferase proteins. We perform a series of classical molecular dynamic simulations and combined quantum and molecular mechanics (QM/MM) calculations to expose the molecular mechanism of C4 carbon atom deprotonation in luciferyl adenylate molecule. QM/MM calculations confirm that ND-protonated His245 residue is a suitable proton acceptor in the wild-type Photinus pyralis luciferase. Classical molecular dynamic simulations reveal oxygen-binding cavities inside the protein including the one located close to the C4 atom of luciferin. In mutant forms that lack direct interactions with the His245 side chain, a proton wire comprising water molecules stimulates either protonation of the phosphate group of the luciferyl adenylate forming an unstable intermediate or keto–enol tautomerisation of luciferin. The comparison of the ionisation potentials of molecular systems with the ‘deprotonated’ C4 carbon atom revealed that the ionisation energy for the enol tautomeric form is close to the system with the His245 proton acceptor. Thus, the existence of the keto–enol tautomerisation channel might explain bioluminescence in case of the absence of the amino acid proton acceptor.

Quantum multi-anomaly detection

A source assumed to prepare a specified reference state sometimes prepares an anomalous one. We address the task of identifying these anomalous states in a series of n preparations with k anomalies. We analyze the minimum-error protocol and the zero-error (unambiguous) protocol and obtain closed expressions for the success probability when both reference and anomalous states are known to the observer and anomalies can appear equally likely in any position of the preparation series. We find the solution using results from association schemes theory, thus establishing a connection between graph theory and quantum hypothesis testing. In particular, we use the Johnson association scheme which arises naturally from the Gram matrix of this problem. We also study the regime of large n and obtain the expression of the success probability that is non-vanishing. Finally, we address the case in which the observer is blind to the reference and the anomalous states. This scenario requires a universal protocol for which we prove that in the asymptotic limit, the success probability corresponds to the average of the known state scenario.

Quantizing Galilean spacetime: a reconstruction of Maxwell’s equations in empty space

As was recently shown, non-relativistic quantum theory can be derived by means of a projection method from a continuum of classical solutions for (massive) particles. In this paper, we show that Maxwell’s equations in empty space can be derived using the same method. In this case, the starting point is a continuum of solutions of equations of motion for massless particles describing the structure of Galilean space-time. As a result of the projection, the space-time structure itself is changed by the appearance of a new fundamental constant c with the dimension of a velocity. This maximum velocity c, derived here for massless particles, is analogous to the accuracy limit ħ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbar $$\\end{document} derived earlier for massive particles. The projection method can thus be interpreted as a generalized quantization. We suspect that all fundamental fields can be traced back to continuous sets of particle trajectories, and that in this sense, the particle concept is more fundamental than the field concept.

Comparison of the effects of Ho: YAG laser virtual Basket™ pulse modulation and Thulium fiber laser on kidney tissue - an ex vivo experimental study.

Through an ex vivo experimental study, we aimed to compare the effects of the Ho: YAG laser Virtual Basket (VB™) modulation and a Thulium fiber laser (TFL) on kidney tissue in different environments and using laser configurations. The 100W Ho: YAG (Cyber Ho, Quanta System, Italy) and 60W TFL (Fiber Dust, Quanta System, Italy) laser devices were used. The following laser settings were selected: power in the range of 10-60W, frequency of 20-40Hz, and energy of 0.5-1-1.5J. A medium pulse duration of 600 µsec was used for VB™, while short (spdTFL; 50 µsec) and long (lpdTFL; 15,000 µsec) were used for TFL. The tissue's incision depth (ID), vaporization area (VA), coagulation area (CA), total laser area (TLA = VA + CA), surface section (SS), and lateral effect (LE) were measured. In total, 108 experiments were conducted. No statistically significant difference in mean VA, TLA, ID, LE, or SS was observed between VB™, spdTFL, and lpdTFL in the low-power output group in saline (p > 0.05). However, the mean CA was statistically significantly higher for VB™ (p = 0.005). In saline and high-power output group, the mean VA, CA, TLA, LE, and ID were higher when using lpdTFL than other pulse durations (p = 0.001, p = 0.001, p = 0.001, p = 0.006, and p = 0.001, respectively). Similar to lpdTFL, VB™ may provide controlled dissection and incision as well as haemostasis. At different laser settings, the individual effects of laser properties (such as pulse length, energy and frequency) on tissue may be more significant.

Quantum gate control of polar molecules with machine learning.

We propose a scheme for achieving basic quantum gates using ultracold polar molecules in pendular states. The qubits are encoded in the YbF molecules trapped in an electric field with a certain gradient and coupled by the dipole-dipole interaction. The time-dependent control sequences consisting of multiple pulses are considered to interact with the pendular qubits. To achieve high-fidelity quantum gates, we map the control problem for the coupled molecular system into a Markov decision process and deal with it using the techniques of deep reinforcement learning (DRL). By training the agents over multiple episodes, the optimal control pulse sequences for the two-qubit gates of NOT, controlled NOT, and Hadamard are discovered with high fidelities. Moreover, the population dynamics of YbF molecules driven by the discovered gate sequences are analyzed in detail. Furthermore, by combining the optimal gate sequences, we successfully simulate the quantum circuit for entanglement. Our findings could offer new insights into efficiently controlling molecular systems for practical molecule-based quantum computing using DRL.

Reductive quantum phase estimation

Estimating a quantum phase is a necessary task in a wide range of fields of quantum science. To accomplish this task, two well-known methods have been developed in distinct contexts, namely, Ramsey interferometry (RI) in atomic and molecular physics and quantum phase estimation (QPE) in quantum computing. We demonstrate that these canonical examples are instances of a larger class of phase estimation protocols, which we call reductive quantum phase estimation (RQPE) circuits. Here, we present an explicit algorithm that allows one to create an RQPE circuit. This circuit distinguishes an arbitrary set of phases with a smaller number of qubits and unitary applications, thereby solving a general class of quantum hypothesis testing to which RI and QPE belong. We further demonstrate a tradeoff between measurement precision and phase distinguishability, which allows one to tune the circuit to be optimal for a specific application. Published by the American Physical Society 2024

Projection hypothesis in the setting for the quantum Jarzynski equality

Projective quantum measurement is a theoretically accepted process in modern quantum mechanics. However, its projection hypothesis is widely regarded as an experimentally established empirical law. In this paper, we combine a previous result regarding the realization of a Hamiltonian process of the projection hypothesis in projective quantum measurement, where the complete set of the orbital observables of the center of mass of a macroscopic quantum mechanical system is restricted to a set of mutually commuting classical observables, and a previous result regarding the work required for an event reading (i.e. the informatical process in projective quantum measurement). Then, a quantum thermodynamic scheme is proposed for experimentally testing these two mutually independent theoretical results of projective quantum measurement simultaneously.

Compatible multilayer magnetic field system for quantum sensing with atoms.

Magnetic fields provide a valuable method to manipulate atomic energy levels and interactions in quantum precision measurements, but achieving precise measurements requires collaboration between the magnetic field system and the optical detection system. We propose a magnetic field system that incorporates a fast-switching magnetic field and an alternating magnetic field. Specifically, we enhance the switching speed by making structural improvements during the switching operation. An independent control approach is employed to reduce the switching time caused by electromagnetic induction across the coil using multilayer coils. The results demonstrate an inverse correlation between the rise and fall times of the magnetic field switch and the number of independently stacked coil layers, indicating the possibility of achieving further improvements in switching speed through structural enhancements. The system developed here has considerable potential for application to diverse quantum systems.

Space-time generalization of mutual information

The mutual information characterizes correlations between spatially separated regions of a system. Yet, in experiments we often measure dynamical correlations, which involve probing operators that are also separated in time. Here, we introduce a space-time generalization of mutual information which, by construction, satisfies several natural properties of the mutual information and at the same time characterizes correlations across subsystems that are separated in time. In particular, this quantity, that we call the space-time mutual information, bounds all dynamical correlations. We construct this quantity based on the idea of the quantum hypothesis testing. As a by-product, our definition provides a transparent interpretation in terms of an experimentally accessible setup. We draw connections with other notions in quantum information theory, such as quantum channel discrimination. Finally, we study the behavior of the space-time mutual information in several settings and contrast its long-time behavior in many-body localizing and thermalizing systems.

Measuring Citation Impact of Bose's Paper Planck's Law and the Light Quantum Hypothesis

Measuring Citation Impact of Bose's Paper Planck's Law and the Light Quantum Hypothesis