Degree Of Indistinguishability Research Articles

Single-shot characterization of photon indistinguishability with dielectric metasurfaces

Characterizing the indistinguishability of photons is a key task in quantum photonics, underpinning the tuning and stabilization of the photon sources and thereby increasing the accuracy of quantum operations. The protocols for measuring the degree of indistinguishability conventionally require photon-coincidence measurements at several different time or phase delays, which is a fundamental bottleneck towards fast measurements and real-time monitoring of indistinguishability. Here, we develop a static dielectric metasurface grating without any reconfigurable elements that realizes a tailored multiport transformation in the free-space configuration without the need for phase locking and enables single-shot characterization of the indistinguishability between two photons in multiple degrees of freedom including time, spectrum, spatial modes, and polarization. Topology optimization is employed to design a silicon metasurface with polarization independence, high transmission, and high tolerance to measurement noise. We fabricate the metasurface and experimentally quantify the indistinguishability of photons in the time domain with fidelity over 98.4%. We anticipate that the developed framework based on ultrathin metasurfaces can be further extended for multi-photon states and additional degrees of freedom associated with spatial modalities.

Generating indistinguishability within identical particle systems: spatial deformations as quantum resource activators.

Identical quantum subsystems can possess a property which does not have any classical counterpart: indistinguishability. As a long-debated phenomenon, identical particles' indistinguishability has been shown to be at the heart of various fundamental physical results. When concerned with the spatial degree of freedom, identical constituents can be made indistinguishable by overlapping their spatial wave functions via appropriately defined spatial deformations. By the laws of quantum mechanics, any measurement designed to resolve a quantity which depends on the spatial degree of freedom only and performed on the regions of overlap is not able to assign the measured outcome to one specific particle within the system. The result is an entangled state where the measured property is shared between the identical constituents. In this work, we present a coherent formalization of the concept of deformation in a general [Formula: see text]-particle scenario, together with a suitable measure of the degree of indistinguishability. We highlight the basic differences with non-identical particles scenarios and discuss the inherent role of spatial deformations as entanglement activators within the spatially localized operations and classical communication operational framework. This article is part of the theme issue 'Identity, individuality and indistinguishability in physics and mathematics'.

Simultaneous quantum estimation of phase and indistinguishability in a two-photon interferometer

With the rapid development of quantum technologies in recent years, the need for high-sensitivity measuring techniques has become a key issue. In particular, optical sensors based on quantum states of light have proven to be optimal resources for high-precision interferometry. Nevertheless, their performance may be severely affected by the presence of noise or imperfections. In this work, we derive the quantum Fisher information matrix associated with the simultaneous estimation of an interferometric phase and the indistinguishability characterizing the probe state consisting of an even number of photons. We find the optimal measurement attaining the ultimate precision for both parameters in a single setup and perform an experiment based on a pair of photons with an unknown degree of indistinguishability entering a two-port interferometer.

Влияние процесса образования единичного кластера радиационных дефектов на переключение состояния транзисторной ячейки памяти

The results of a study of the optical characteristics of non-classical light sources based on single In(Ga)As quantum dot grown on a (111)B GaAs substrate are presented. The single-photon nature of the radiation is confirmed by measuring and analyzing the second-order correlation function g(2)(τ), g(2)(0)=0.033 ± 0.027, and the degree of indistinguishability of sequentially emitted single photons is (41 ± 10 )%.

Однофотонное излучение InGaAs-квантовой точки, выращенной на подложке (111)B GaAs

The results of a study of the optical characteristics of non-classical light sources based on single In(Ga)As quantum dot grown on a (111)B GaAs substrate are presented. The single-photon nature of the radiation is confirmed by measuring and analyzing the second-order correlation function g(2)(τ), g(2)(0)=0.033 ± 0.027, and the degree of indistinguishability of sequentially emitted single photons is (41 ± 10 )%.

Demultiplexed single-photon source with a quantum dot coupled to microresonator

The characteristics of a single-photon emitter based on a semiconductor quantum dot, such as their indistinguishability and brightness, depend on the stability of the recombination channel, which can switch spontaneously between exciton and trion. We show that dominant recombination through neutral exciton states can be achieved by careful control of the doping profile near an epitaxial InAs/GaAs quantum dot placed in a columnar microcavity with distributed Bragg reflectors. The Hong-Ou-Mandel experiments carried out in the fabricated device demonstrate the degree of indistinguishability of 91% of successively emitted single photons within 242 ns at an efficiency of 10% inside a single-mode optical fiber. The achieved brightness made it possible to implement spatio-temporal demultiplexing of photons in six independent spatial modes with an in-fiber generation frequency of more than 0.1 Hz.

Derivation of a statistical model for classical systems obeying the fractional exclusion principle.

The violation of the Pauli principle has been surmised in several models of the fractional exclusion statistics and successfully applied to several quantum systems. In this paper, a classical alternative of the exclusion statistics is studied using the maximum entropy methods. The difference between the Bose-Einstein statistics and the Maxwell-Boltzmann statistics is understood in terms of a separable quantity, namely the degree of indistinguishability. Starting from the usual Maxwell-Boltzmann microstate counting formula, a special restriction related to the degree of indistinguishability is incorporated using Lagrange multipliers to derive the probability distribution function at equilibrium under NVE conditions. It is found that the resulting probability distribution function generates real positive values within the permissible range of parameters. For a dilute system, the probability distribution function is intermediate between the Fermi-Dirac and Bose-Einstein statistics and follows the exclusion principle. Properties of various variables of this novel statistical model are studied and possible application to classical thermodynamics is discussed.

DMD, RIPK3, and MLKL gene editing by CRISPR Cas9 as myofiber protection against dystrophin deficiency and necroptosis in Duchenne muscular dystrophy: A literature review


 BACKGROUND: Duchenne muscular dystrophy is a neuromuscular disease caused by a deficiency of dystrophin, which causes the skeletal and cardiac muscles to degenerate. Targeted deletion of DMD, RIPK3, and MLKL has been shown in several studies to prevent dystrophin deficiency and necroptosis, a critical hypothesis in the etiology of Duchenne muscular dystrophy. AIM: This research aimed to see if using CRISPR/Cas9 to target DMD, RIPK3, and MLKL is an effective therapeutic and if it has a long-term effect on Duchenne muscular dystrophy. METHODS: Abstracts and titles of articles were searched for specific keywords to summarize them using the method used in this study. The researcher will look over the entire article to see if it is valuable and relevant to the topic. RESULTS: CRISPR/Cas9-mediated genome editing in MDX mice can improve the primary genetic lesions that cause muscular dystrophy (DMD) and prevent disease development. Furthermore, Ripk3/Mlk1 double knockout completely blocked necroptosis susceptibility in necroptosis-sensitive cell lines, each to an indistinguishable degree. CONCLUSION: DMD, RIPK3, and MLKL gene editing by CRISPR/Cas9 is effective dystrophin insufficiency, sarcolemma fragility, poor intracellular signaling, myocyte death, inflammatory infiltration, muscle replacement, and necroptosis. However, more research is needed to determine its side effects and safety.

3D Geo-Indistinguishability for Indoor Location-Based Services

Indoor location-based services (LBS) are widely used in large-scale indoor buildings, such as high-rise hospitals and multi-story shopping malls. At the same time, location privacy protection in such three-dimensional (3D) space has recently attracted considerable attention. Currently, most existing location privacy protection schemes focus on two-dimensional (2D) location protection and fail to prevent location inference attacks when the user’s location data include height dimension, i.e., 3D geolocation. Enlightened by the concept of differential privacy, in this paper we first study the impact factors of the degree of indistinguishability of 3D geolocations. Then, we quantify location privacy for LBS applications in the 3D space with geo-indistinguishability (3D-GI) rigorously and provably. We develop a mechanism of three-variates Laplacian to generate perturbed locations considering the locations’ X, Y, and Z-coordinates simultaneously, guaranteeing geo-indistinguishability. Furthermore, the discretization noise-adding mechanism is studied to satisfy geo-indistinguishability in the 3D space under the finite precision of hardware/devices. Considering the discretized mechanism can only satisfy geo-indistinguishability in finite 3D space and users visit the limited regions, we further study the truncation of the Laplacian mechanism to limit the generated perturbed locations within a specific region. Simulation results demonstrate that the proposed 3D-GI outperforms the benchmarks while guaranteeing privacy regardless of the adversary’s prior knowledge.

Coherence and path indistinguishability for the interference of multiple single-mode fields

A well-known result for the interference of two single-mode fields is that the degree of coherence and the degree of indistinguishability are the same when we consider the detection of a single photon. In this article, we present the relation between the degree of coherence, path indistinguishability and the fringe visibility considering interference of multiple numbers of single-mode fields while being interested in the detection of a single photon only. We will also mention how Born’s rule of interference for multiple sources is reflected in these results.

Triggered Single‐Photon Emission of Resonantly Excited Quantum Dots Grown on (111)B GaAs Substrate

In the recent decades, semiconductor quantum dots (QDs) have proven to be valuable candidates as sources for various photonic applications. Of particular interest are, due to their wide‐ranging applicability in quantum communication and computation, indistinguishable photons as well as entangled photon pairs, which can be emitted on demand. The latter require highly symmetric QDs with a small to vanishing excitonic fine‐structure splitting. Herein, quantum optical properties of QDs grown via molecular‐beam epitaxy (MBE) on (111)B‐GaAs substrate are reported to study their emission in terms of triggered single‐photon emission under quasi‐resonant p‐shell excitation, and under strict resonant s‐shell excitation. The investigations reveal very good emission properties of these types of QDs, especially under s‐shell resonant excitation. In fact, the results yield almost background‐free triggered single photons with excellent multiphoton suppression associated with g(2)(0) = (0.033 ± 0.027) and a degree of indistinguishability of (41 ± 10)%. The achieved results underline the high optical quality of (111)‐QDs and show their high potential for applications in photonic quantum technologies.

A Pure and Indistinguishable Single‐Photon Source at Telecommunication Wavelength

AbstractOn‐demand single‐photon sources emitting pure and indistinguishable photons at the telecommunication wavelength are critical assets toward the deployment of fiber‐based quantum networks. Indeed, single photons may serve as flying qubits, allowing communication of quantum information over long distances. Self‐assembled InAs quantum dots embedded in GaAs constitute an excellent nearly deterministic source of high‐quality single photons, but the vast majority of sources operate in the 900–950 nm wavelength range, precluding their adoption in a quantum network. A quantum frequency conversion scheme is presented here for converting single photons from quantum dots to the telecommunication C band, around 1550 nm, achieving 40.8% end‐to‐end efficiency, while maintaining both high purity and a high degree of indistinguishability during conversion with measured values of and , respectively.

Multi-source unsupervised domain adaptation for object detection

Domain adaptation for object detection has been extensively studied in recent years. Most existing approaches focus on single-source unsupervised domain adaptive object detection. However, a more practical scenario is that the labeled source data is collected from multiple domains with different feature distributions. The conventional approaches do not work very well since multiple domain gaps exist. We propose a Multi-source domain Knowledge Transfer (MKT) method to handle this situation. First, the low-level features from multiple domains are aligned by learning a shallow feature extraction network. Then, the high-level features from each pair of source and target domains are aligned by the followed multi-branch network. After that, we perform two parts of information fusion: (1) We train a detection network shared by all branches based on the transferability of each source sample feature. The transferability of a source sample feature means the indistinguishable degree to the target domain sample features. (2) For using our model, the target sample features output by the multi-branch network are fused based on the average transferability of each domain. Moreover, we leverage both image-level and instance-level attention to promote positive cross-domain transfer and suppress negative transfer. Our main contributions are the two-stage feature alignments and information fusion. Extensive experimental results on various transfer scenarios show that our method achieves the state-of-the-art performance.

Representation of the Universe as a Dendrogramic Hologram Endowed with Relational Interpretation

A proposal for a fundamental theory is described in which classical and quantum physics as a representation of the universe as a gigantic dendrogram are unified. The latter is the explicate order structure corresponding to the purely number-theoretical implicate order structure given by p-adic numbers. This number field was zero-dimensional, totally disconnected, and disordered. Physical systems (such as electrons, photons) are sub-dendrograms of the universal dendrogram. Measurement process is described as interactions among dendrograms; in particular, quantum measurement problems can be resolved using this process. The theory is realistic, but realism is expressed via the the Leibniz principle of the Identity of Indiscernibles. The classical-quantum interplay is based on the degree of indistinguishability between dendrograms (in which the ergodicity assumption is removed). Depending on this degree, some physical quantities behave more or less in a quantum manner (versus classic manner). Conceptually, our theory is very close to Smolin’s dynamics of difference and Rovelli’s relational quantum mechanics. The presence of classical behavior in nature implies a finiteness of the Universe-dendrogram. (Infinite Universe is considered to be purely quantum.) Reconstruction of events in a four-dimensional space type is based on the holographic principle. Our model reproduces Bell-type correlations in the dendrogramic framework. By adjusting dendrogram complexity, violation of the Bell inequality can be made larger or smaller.

Crux of Using the Cascaded Emission of a Three-Level Quantum Ladder System to Generate Indistinguishable Photons.

We investigate the degree of indistinguishability of cascaded photons emitted from a three-level quantum ladder system; in our case the biexciton-exciton cascade of semiconductor quantum dots. For the three-level quantum ladder system we theoretically demonstrate that the indistinguishability is inherently limited for both emitted photons and determined by the ratio of the lifetimes of the excited and intermediate states. We experimentally confirm this finding by comparing the quantum interference visibility of noncascaded emission and cascaded emission from the same semiconductor quantum dot. Quantum optical simulations produce very good agreement with the measurements and allow us to explore a large parameter space. Based on our model, we propose photonic structures to optimize the lifetime ratio and overcome the limited indistinguishability of cascaded photon emission from a three-level quantum ladder system.

Experimental quantification of four-photon indistinguishability

Photon indistinguishability plays a fundamental role in information processing, with applications such as linear-optical quantum computation and metrology. It is then necessary to develop appropriate tools to quantify the amount of this resource in a multiparticle scenario. Here we report a four-photon experiment in a linear-optical interferometer designed to simultaneously estimate the degree of indistinguishability between three pairs of photons. The interferometer design dispenses with the need of heralding for parametric down-conversion sources, resulting in an efficient and reliable optical scheme. We then use a recently proposed theoretical framework to quantify four-photon indistinguishability, as well as to obtain bounds on three unmeasured two-photon overlaps. Our findings are in high agreement with the theory, and represent a new resource-effective technique for the characterization of multiphoton interference.

Field measurement study on time-varying characteristics of modal parameters of super high-rise buildings during super typhoon

This study identifies the modal parameters of four super high-rise buildings in Shenzhen and analyzes the variation of their structural dynamic properties with amplitude and time based on the long-term field data of Super Typhoon Mangkhut. Results show the maximum acceleration of the four buildings is 13.29–41.96 milli-g and occurs at the maximum wind speed period. In the early stage, as the wind speed increases with time, structural modal frequencies decrease and reach the minimum during the maximum wind speed period. Subsequently, wind speed gradually decreases, modal frequencies increase slowly, and the highest ratio of frequency change is 11.9%. The change of damping ratio is somewhat stochastic but overall first increases and then decreases with time. The mode shapes of most buildings remain basically unchanged during typhoon. However, the mode shapes of the building with the maximum response differ greatly at the maximum and the low wind speeds. Besides, the two-order modal frequencies drop sharply near the maximum wind speed and approach one another to an indistinguishable degree. These new results and rules of modal parameters have important reference values for the further research on the influence of wind–structure interaction on structural wind effect and subsequent wind-induced vibration control.

Role of indistinguishability in interferometric phase estimation

We report a theoretical and experimental study on the role of indistinguishability in the estimation of an interferometric phase. In particular, we show that the quantum Fisher information, which limits the maximum precision achievable in the parameter estimation, increases linearly with respect to the degree of indistinguishability between the input photons in a two-port interferometer, in the ideal case of a pure probe state. We experimentally address the role played by the indistinguishability for the case of two photons entering a polarization-based interferometer, where the degree of indistinguishability is characterized by the overlap between two spatial modes. The experimental results support the fact that, even in the presence of white noise, a quantum enhancement in the interferometric phase estimation can be obtained from a minimum degree of indistinguishability.

Temporally multimode four-photon Hong-Ou-Mandel interference

The two-photon Hong-Ou-Mandel (HOM) interference is a pure quantum effect which indicates the degree of indistinguishability of photons. The four-photon HOM interference exhibits richer dynamics in comparison to the two-photon interference and simultaneously is more sensitive to the input photon states. We demonstrate theoretically and experimentally an explicit dependency of the four-photon interference to the number of temporal modes, created in the process of parametric down-conversion. Moreover, we exploit the splitting ratio of the beam splitter to manipulate the interference between bunching and antibunching. Our results reveal that the temporal mode structure (multimodeness) of the quantum states shapes many-particle interference.

Highly indistinguishable single photons from incoherently excited quantum dots

Semiconductor quantum dots are converging towards the demanding requirements of photonic quantum technologies. Among different systems, quantum dots with dimensions exceeding the free-exciton Bohr radius are appealing because of their high oscillator strengths. While this property has received much attention in the context of cavity quantum electrodynamics, little is known about the degree of indistinguishability of single photons consecutively emitted by such dots and on the proper excitation schemes to achieve high indistinguishability. A prominent example is represented by GaAs quantum dots obtained by local droplet etching, which recently outperformed other systems as triggered sources of entangled photon pairs. On these dots, we compare different single-photon excitation mechanisms, and we find (i) a "phonon bottleneck" and poor indistinguishability for conventional excitation via excited states and (ii) photon indistinguishablilities above 90% for both strictly resonant and for incoherent acoustic- and optical-phonon-assisted excitation. Among the excitation schemes, optical phonon-assisted excitation enables straightforward laser rejection without a compromise on the source brightness together with a high photon indistinguishability.