Nonclassical Features Research Articles

Nonclassicality of photons in mean-field anisotropic quantum light-matter interacting lattices: Two-photon correlation function and quadrature squeezing

Abstract The generation of nonclassical photons via quantum light-matter interactions is of fundamental importance in quantum optics. Here we investigate steady-state two-photon correlation function and photon squeezing in an open anisotropic Rabi lattice by applying quantum dressed master equation embedded with the mean-field approximation. The expanded antibunching effect of photons due to anisotropic qubit-photon interaction, is strongly suppressed by including inter-site photon tunneling, whereas the giant photon bunching keeps robust with weak inter-site photon tunneling strength. The microscopic processes for photon antibunching and bunching effects are presented based on incoherent transitions between eigenstates. The photon squeezing is also analyzed under the influences of qubit-photon coupling and anisotropic factor. The quadrature squeezing shows persistency by tuning on the inter-site photon tunneling, and becomes dramatically pronounced at the small anisotropic factor. Moreover, the increasing number of qubits significantly enhances quadrature squeezing with strong qubit-photon interaction. We hope such results may provide physical insights into efficient generation and manipulation of nonclassical features of photons in quantum light-matter interacting lattice systems.

Parity symmetry breaking of spin-j coherent state superpositions in Gaussian noise channel

Abstract The Wigner function and Wigner-Yanase skew information are connected through quantum coherence. States with high skew information often exhibit more pronounced negative regions in their Wigner functions, indicative of quantum interference and non-classical behavior. Thus, the relationship between these two concepts is that states with high quantum coherence tend to display more non-classical features in their Wigner functions. By exploiting this relationship, which manifests as parity symmetry and asymmetry, we analyze parity symmetry and asymmetry in the superposition of two spin coherent states for a spin-$1/2$, as well as for a general spin-$j$. This analysis shows that the preservation of the parity asymmetry, or the violation of the parity symmetry, correlates with an increase in the value of spin $j$. Additionally, we investigate the behavior of parity symmetry and asymmetry of these states subjected to a Gaussian noise channel. Specifically, we examine how this parity symmetry and asymmetry change and identify the points at which parity symmetry is violated in the spin-$1/2$ cat state. Notably, the violation of parity symmetry becomes more pronounced at higher values of the decoherence parameter $s$. Our study shows how the spin value $j$ affects the breaking of parity symmetry in general spin-$j$ cat states that are hit by Gaussian noise.

A deep-learning-based model for assessment of autoimmune hepatitis from histology: AI(H).

Histological assessment of autoimmune hepatitis (AIH) is challenging. As one of the possible results of these challenges, nonclassical features such as bile-duct injury stays understudied in AIH. We aim to develop a deep learning tool (artificial intelligence for autoimmune hepatitis [AI(H)]) that analyzes the liver biopsies and provides reproducible, quantifiable, and interpretable results directly from routine pathology slides. A total of 123 pre-treatment liver biopsies, whole-slide images with confirmed AIH diagnosis from the archives of the Institute of Pathology at University Hospital Basel, were used to train several convolutional neural network models in the Aiforia artificial intelligence (AI) platform. The performance of AI models was evaluated on independent test set slides against pathologist's manual annotations. The AI models were 99.4%, 88.0%, 83.9%, 81.7%, and 79.2% accurate (ratios of correct predictions) for tissue detection, liver microanatomy, necroinflammation features, bile duct damage detection, and portal inflammation detection, respectively, on hematoxylin and eosin-stained slides. Additionally, the immune cells model could detect and classify different immune cells (lymphocyte, plasma cell, macrophage, eosinophil, and neutrophil) with 72.4% accuracy. On Sirius red-stained slides, the test accuracies were 99.4%, 94.0%, and 87.6% for tissue detection, liver microanatomy, and fibrosis detection, respectively. Additionally, AI(H) showed bile duct injury in 81 AIH cases (68.6%). The AI models were found to be accurate and efficient in predicting various morphological components of AIH biopsies. The computational analysis of biopsy slides provides detailed spatial and density data of immune cells in AIH landscape, which is difficult by manual counting. AI(H) can aid in improving the reproducibility of AIH biopsy assessment and bring new descriptive and quantitative aspects to AIH histology.

Role of coherence in many-body Quantum Reservoir Computing

Quantum Reservoir Computing (QRC) offers potential advantages over classical reservoir computing, including inherent processing of quantum inputs and a vast Hilbert space for state exploration. Yet, the relation between the performance of reservoirs based on complex and many-body quantum systems and non-classical state features is not established. Through an extensive analysis of QRC based on a transverse-field Ising model we show how different quantum effects, such as quantum coherence and correlations, contribute to improving the performance in temporal tasks, as measured by the Information Processing Capacity. Additionally, we critically assess the impact of finite measurement resources and noise on the reservoir’s dynamics in different regimes, quantifying the limited ability to exploit quantum effects for increasing damping and noise strengths. Our results reveal a monotonic relationship between reservoir performance and coherence, along with the importance of quantum effects in the ergodic regime.

Evidence of the Quantum Optical Nature of High-Harmonic Generation

High-harmonic generation is a light up-conversion process occurring in a strong laser field, leading to coherent bursts of extreme ultrashort broadband radiation [Lewenstein , Phys. Rev. A , 2117 (1994)]. As a new perspective, we propose that ultrafast strong-field electronic or photonic processes such as high-harmonic generation can potentially generate nonclassical states of light well before the decoherence of the system occurs [Gorlach , Nat. Commun. , 4598 (2020); Stammer ., Phys. Rev. Lett. , 123603 (2022)]. This could address fundamental challenges in quantum technology such as scalability, decoherence, or the generation of massively entangled states [Lewenstein , Luca Argenti Michael Chini, 27 (2024)]. Here, we report experimental evidence of the nonclassical nature of the harmonic emission in several semiconductors excited by a femtosecond infrared laser. By investigating single- and double-beam intensity cross-correlation [Loudon, Rep. Prog. Phys. , 913 (1980)], we measure characteristic nonclassical features in the single-photon statistics. We observe two-mode squeezing in the generated harmonic radiation, which depends on the laser intensity that governs the transition from super-Poissonian to Poissonian photon statistics. The measured violation of the Cauchy-Schwarz inequality realizes a direct test of multipartite entanglement in high-harmonic generation [Wasak, Phys. Rev. A , 033616 (2014)]. This result is supported by the theory of multimodal detection and the Hamiltonian from which the effective squeezing modes of the harmonics can be derived [Gonoskov , Phys. Rev. B , 125110 (2024); Christ New J. Phys. , 033027 (2011)]. With this work, we show experimentally that high-harmonic generation is a new quantum bosonic platform that intrinsically produces nonclassical states of light with unique features such as multipartite broadband entanglement or multimode squeezing. The source operates at room temperature, using standard semiconductors and a standard commercial fiber laser, opening up new routes for the quantum industry, such as optical quantum computing, communication, and imaging. Published by the American Physical Society 2024

Non-classical event-related potentials reveal attention network alteration in patients with temporal lobe epilepsy

ObjectiveTo explore the characteristic changes of multiple ERP components associated with attention impairments in patients with temporal lobe epilepsy (TLE). MethodsA total of 92 patients diagnosed with TLE at Xiangya Hospital during May 2022 and January 2023 and 85 healthy controls were included in this study. Participants were asked to complete attention network test with recording of electroencephalogram. ResultsCompared with healthy controls, significant lower amplitudes (cue-related N1, N2 and CNV) and longer latencies (target-related N2) were found in TLE patients. Besides classical components, other components could also reveal the impairments of attention function. Cue-related N1 (p ≤ 0.007) and N2 (p ≤ 0.01) components indicated impaired alerting and orienting network in TLE. And cue-related CNV-E component (p = 0.003) promoted the alerting network was damaged and target-related N2 component (p = 0.008) indicated the executive control network was impaired. ConclusionThese findings consummate the non-classical ERP features of attention impairments in TLE patients. SignificanceThe above findings have strong clinical guiding significance for early identification and intervention.

Revealing nonclassicality of multiphoton optical beams via artificial neural networks

The identification of nonclassical features of multiphoton quantum states represents a crucial task in the development of many quantum photonic technologies. Under realistic experimental conditions, a photonic quantum state gets affected by its interaction with several nonideal optoelectronic devices, including those used to guide, detect, or characterize it. The result of such noisy interaction is that the nonclassical features of the original quantum state get considerably reduced or are completely absent in the detected, final state. In this work, the self-learning features of artificial neural networks are exploited to experimentally show that the nonclassicality of multiphoton quantum states can be assessed and fully characterized, even in the cases in which the nonclassical features are concealed by the measuring devices. Our work paves the way toward artificial-intelligence-assisted experimental-setup characterization, as well as quantum state nonclassicality identification. Published by the American Physical Society 2024

Entanglement signature in quantum work statistics in the slow-driving regime

In slowly driven classical systems, work is a stochastic quantity and its probability distribution is known to satisfy the work fluctuation-dissipation relation, which states that the mean and variance of the dissipated work are linearly related. Recently, it was shown that generation of quantum coherence in the instantaneous energy eigenbasis leads to a correction to this linear relation in the slow-driving regime. Here, we go even further by investigating nonclassical features of work fluctuations in setups with more than one system. To do this, we first generalize slow control protocols to encompass multipartite systems, allowing for the generation of quantum correlations during the driving process. Then, focusing on two-qubit systems, we show that entanglement generation leads to a positive contribution to the dissipated work, which is distinct from the quantum correction due to local coherence generation known from previous work. Our results show that entanglement generated during slow control protocols, e.g., as an unavoidable consequence of qubit crosstalk, comes at the cost of increased dissipation. Published by the American Physical Society 2024

Primary hyperparathyroidism: from guidelines to outpatient clinic.

Primary hyperparathyroidism (PHPT) is a common endocrine disease characterized by hypercalcemia due to inappropriately high parathyroid hormone secretion. While in the typical, symptomatic form of the disease diagnosis is set easily and standard management is surgical removal of the hyperfunctioning parathyroid (HP), this may not be the case in more subtle forms of PHPT, such as the asymptomatic and the normocalcemic PHPT. Localization of the HP could also be challenging, especially in small-sized adenomas, ectopic lesions or multiglandular disease. An experienced surgical team is essential to achieve curative parathyroidectomy. In this article, we used illustrative clinical vignettes to dissect the approach to the patient with PHPT, from the diagnosis establishment to the suggested investigation to identify classical and non-classical PHPT features and the methodology to locate the abnormal tissue. Accordingly, we elaborated on appropriate management, both surgical and conservative.

Compasslike states in a thermal reservoir and fragility of their nonclassical features

Compasslike states in a thermal reservoir and fragility of their nonclassical features

The Mth nonlinear coherent states

Since radiation field states are very important in the interaction with the various atomic structures, in this article we introduce a new type of quantum states, which we call ‘Mth nonlinear coherent states’. We define these states based on acting of the number operator M times nˆM on a nonlinear coherent state. By analyzing the photon distribution function and its overlap with the nonlinear coherent states, it becomes clear that these states are very similar to the corresponding nonlinear coherent states. We also investigate the nonclassical features of such states for different values of M, and it is determined that the occurrence of sub-Poissonian photon statistics, normal squeezing, and amplitude squared squeezing are considerable nonclassical properties of the Mth nonlinear coherent states. Also, examining the Husimi function shows a local behavior for the introduced states. Furthermore, by calculating the Wigner function, we find out that in some points of the phase space, the value of this function is negative which could be considered as a nonclassical feature for these states.

Generating superposition of squeezed states and photon-added squeezed states

The scheme of an arrangement is considered for the preparation of some non-classical superposed states from squeezed states by using the optical parametric amplifier (OPA) apparatus, which is based on an idea recently proposed to generate photon-added states from the coherent states of light. This technique allows one to obtain linear combinations of squeezed vacuum states (SVSs) and n-photon-added squeezed vacuum states (n-PASVSs), that can enrich the non-classicality of the SVSs and n-PASVSs and improve their performances in quantum information protocols. Their characteristics are greatly affected by the gain of the OPA and the coherent field amplitude (or, mean number of photons). For this purpose, a comprehensive analysis of the non-classical features of these states has been presented in four different behavioral regimes, i.e. low- and high-gain regimes in the presence of weak and strong coherent fields. Finally, the role of the gain parameter of the light state from OPA as one of the input states of the Mach–Zehnder interferometer (MZI) apparatus in phase sensitivity optimization is discussed.

The entanglement and nonclassical properties of multi-photon amplified added based two-mode entangled coherent states

We explore into the non-classical characteristics of a new entangled coherent state (CS), also known as a multi-photon addition amplified coherent state (MPAACS) gn̂â†m, which is produced by adding any quantity of photons to two-mode coherent states with various gain factor values. A superposition of photon-added amplified two-mode CSs (MPAACS) also exists in this novel entangled state. It is proven that the gain factor and Laguerre polynomials are related to the MPAACS normalization factor. Analytical discussion is also had regarding entanglement and quantum statistical properties. Regarding concurrence, our findings further suggest that by selecting suitable values for the gain factor g, photon added (m,n), and coherent amplitude, entanglement for the output state can occur. Specifically, the enhancement of the entanglement can be found at large g values at fixed (m,n) in comparison to (m,n) values at fixed g and small amplitude with ϕ=0 or pi. Besides that, the analyses of nonclassicality reveal that, when comparing the results for several values (m,n) at fixed g and with several values g at fixed (m,n), the low-order antibunching effect, the cross-correlation function, and the Wigner function all support the sub-Poissonian statistics. When analyses of the nonclassicality and the negative value of the WF for ϕ=0 are larger at fixed parameter (m,n), but larger at g fixed for ϕ=π, the TMAA-TMC states perform better.

Modeling of fluctuations in dynamical optoelectronic device simulations within a Maxwell-density matrix Langevin approach

We present a full-wave Maxwell-density matrix simulation tool including c-number stochastic noise terms for the modeling of the spatiotemporal dynamics in active photonic devices, such as quantum cascade lasers and quantum dot structures. The coherent light–matter interaction in such devices plays an important role in the generation of frequency combs and other nonlinear and non-classical optical phenomena. Since the emergence of nonlinear and non-classical features is directly linked to the noise properties, detailed simulations of the noise characteristics are required for the development of low-noise quantum optoelectronic sources. Our semiclassical simulation framework is based on the Lindblad equation for the electron dynamics, coupled with Maxwell’s equations for optical propagation in the laser waveguide. Fluctuations arising from the interactions of the optical field and quantum system with their reservoirs are treated within the quantum Langevin theory. Here, the fluctuations are included by adding stochastic c-number terms to the Maxwell-density matrix equations. The implementation in the mbsolve dynamic simulation framework is publicly available.

Psoriazis hastalarında klasik/klasik olmayan histopatolojik bulguların psoriasis alt tiplerine, hastalık süresine ve şiddetine, anatomik bölgeye ve klinik görünüme göre değişimi

Objective: Although histopathological examination is considered the gold standard in the diagnosis of psoriasis, it has limited usefulness in patients with non-classical histopathological and/or clinical presentations. The aim of this study was to examine the distribution of classical and non-classical histopathological findings according to psoriasis subtype, disease duration, disease severity, biopsy site, and classical/non-classical presentation.
 Methods: We retrospectively reviewed the records of 160 patients with histopathologically confirmed psoriasis. Classical and non-classical histopathological features were determined according to dermatopathology textbooks and literature. Patients were categorized according to disease duration (≤12 and >12 months) and disease severity (Psoriasis Area Severity Index [PASI] ≤10 and >10) at presentation, and classical/non-classical presentation (based on morphology, distribution, nail pitting, and family history).
 Results: The most common classical histopathological findings were regular acanthosis (99.4%), confluent parakeratosis (96.3%), blood vessels, dilated (93.1%), hyperkeratosis (89.4%), and suprapapapillary plate thinning (89.4%). The most common non-classical histopathological findings were superficial perivascular dermal infiltration (81.3%) and spongiosis (53.8%). Hyperkeratosis (p=0.044) and intraepidermal lymphocyte accumulation (p=0.042) were more frequent in patients with a disease duration >12 months. The presence of Munro microabscess (p=0.010) and stratum basale necrotic keratinocytes (p=0.031) were observed more frequently in patients with PASI >10. Significant hyperkeratosis (p=0.024) and suprapapillary plate thinning (p=0.027) were more common in trunk biopsies compared to other locations. Spongiosis (p=0.005) and intraepidermal lymphocytes (p=0.008) were more common in patients with non-classical clinical presentation.
 Conclusion: Non-classical histopathological findings can be observed in patients with psoriasis. Clinical features should be considered when evaluating classical/non-classical histopathological findings during diagnosis.

Entropic uncertainty relations for multiple measurements assigned with biased weights

The entropic way of formulating Heisenberg's uncertainty principle not only plays a fundamental role in applications of quantum information theory but also is essential for manifesting genuine nonclassical features of quantum systems. In this paper we investigate Rényi entropic uncertainty relations (EURs) in the scenario where measurements on individual copies of a quantum system are selected with nonuniform probabilities. In contrast with EURs that characterize an observer's overall lack of information about outcomes with respect to a collection of measurements, we establish state-dependent lower bounds on the weighted sum of entropies over multiple measurements. Conventional EURs thus correspond to the special cases when all weights are equal, and in such cases we show our results are generally stronger than previous ones. Moreover, taking the entropic steering criterion as an example, we numerically verify that our EURs could be advantageous in practical quantum tasks by optimizing the weights assigned to different measurements. Importantly, this optimization does not require quantum resources and is efficiently computable on classical computers. Published by the American Physical Society 2024

Optomechanical squeezing and entanglement in cavities optomechanical system

We present the squeezing and entanglement features of the vibrational phonon modes in a double-cavity optomechanical system with input squeezed light. The non-classical features of the vibrational phonon modes arise from the transfer of quantum coherence from the optical to the phonon modes. The phonon modes exhibit squeezing, and the degree of squeezing increases with the increase in the input squeezed light. To quantify the entanglement between the phonon modes, we apply the Hillery and Zubairy criterion. We demonstrate that the entanglement between the phonon modes increases with an increase in optomechanical cooperativity. Moreover, the input squeezed light has a substantial effect on the degree entanglement between the phonon modes.

Semiclassical gravity beyond coherent states

We show that it is possible to still use semiclassical gravity together with quantum field theory beyond the regimes where the field state is coherent. In particular, we identify families of cat states (superposition of almost-distinguishable coherent states that have very non-classical features) for which the gravitational backreaction can be modeled by semiclassical gravity.

Preparation of non-Gaussian states based on three-photon quantum scissors

We investigate the properties of non-Gaussian quantum states generated by a three-photon quantum scissor (3-QS). Three different types of inputs to the 3-QS are considered: coherent state (CS), squeezed vacuum state (SVS), and optical field thermal state (TS). We discuss both the detection probability and fidelity of the output states. Our results demonstrate that when the input states have a smaller mean photon number, the output non-Gaussian state can exhibit high detection probability and high fidelity by selecting an appropriate transmissivity. Additionally, we calculate the Wigner functions for the various output states and analyze the non-classical properties by comparing the negative volume of the Wigner functions. The results indicate that the output non-Gaussian states display significant non-classical behavior, particularly when the transmissivity is high, with SVS as the input state showing the strongest effect. Moreover, we compare the performance of the 3-QS with that of the two-photon quantum scissors (2-QS). The findings demonstrate that the non-Gaussian states prepared by the 3-QS possess stronger non-classical characteristics. These results have potential implications for advancing the practical application of the 3-QS in quantum information technology.

Kirkwood-Dirac quasiprobability approach to the statistics of incompatible observables

Recent work has revealed the central role played by the Kirkwood-Dirac quasiprobability (KDQ) as a tool to properly account for non-classical features in the context of condensed matter physics (scrambling, dynamical phase transitions) metrology (standard and post-selected), thermodynamics (power output and fluctuation theorems), foundations (contextuality, anomalous weak values) and more. Given the growing relevance of the KDQ across the quantum sciences, our aim is two-fold: First, we highlight the role played by quasiprobabilities in characterizing the statistics of quantum observables and processes in the presence of measurement incompatibility. In this way, we show how the KDQ naturally underpins and unifies quantum correlators, quantum currents, Loschmidt echoes, and weak values. Second, we provide novel theoretical and experimental perspectives by discussing a wide variety of schemes to access the KDQ and its non-classicality features.