Pub Date : 2024-09-17DOI: 10.1103/physreva.110.032215
Maximilian Schlosshauer
We compare the performance of protective quantum measurements to that of standard projective measurements. Performance is quantified in terms of the uncertainty in the measured expectation value. We derive an expression for the relative performance of these two types of quantum measurements and show explicitly that protective measurements can provide a significant performance advantage over standard projective measurements.
{"title":"Performance advantage of protective quantum measurements","authors":"Maximilian Schlosshauer","doi":"10.1103/physreva.110.032215","DOIUrl":"https://doi.org/10.1103/physreva.110.032215","url":null,"abstract":"We compare the performance of protective quantum measurements to that of standard projective measurements. Performance is quantified in terms of the uncertainty in the measured expectation value. We derive an expression for the relative performance of these two types of quantum measurements and show explicitly that protective measurements can provide a significant performance advantage over standard projective measurements.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"71 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1103/physreva.110.033714
S. Samimi, M. M. Golshan
In the present work, the role of temperature in the occurrence of optical phases in a system of a large number of atoms interacting with photons is reported. To this end, it is assumed that the cavity inside which the constituents interact is in equilibrium with a heat reservoir, held at a fixed temperature. To achieve this goal, we start with the conventional density operator to calculate the mean values of electromagnetic quadratures. To make the realization of three distinct optical phases, trivial, electric, and magnetic superradiance, possible, the medium inside the cavity is assumed to be a second-order nonlinear one. The nonlinearity of the medium is further assumed to be activated by an externally applied classical pump field. As a consequence, now there are two external controlling agents, the temperature and nonlinearity strength. We then proceed to calculate the quadrature mean values in the thermodynamical limit and for a large number of atoms as a function of temperature. An analysis of the calculated mean values, along with relevant figures, reveals temperature-dependent conditions for realizing trivial, electric, and magnetic optical phases. Moreover, we shall demonstrate that the atom-field coupling strength gives rise to two distinct regimes where the optical phases behave quite differently. In one of the two regimes it is possible for the phases to coexist, while in the other it is not. As a profound result, it is demonstrated that for such a system there can exist a unique temperature (triple point) at which the three optical phases coexist.
{"title":"Temperature dependence of optical phase transitions in a system of two-level atoms and photons interacting inside a nonlinear cavity","authors":"S. Samimi, M. M. Golshan","doi":"10.1103/physreva.110.033714","DOIUrl":"https://doi.org/10.1103/physreva.110.033714","url":null,"abstract":"In the present work, the role of temperature in the occurrence of optical phases in a system of a large number of atoms interacting with photons is reported. To this end, it is assumed that the cavity inside which the constituents interact is in equilibrium with a heat reservoir, held at a <i>fixed temperature</i>. To achieve this goal, we start with the conventional density operator to calculate the mean values of electromagnetic quadratures. To make the realization of three distinct optical phases, trivial, electric, and magnetic superradiance, possible, the medium inside the cavity is assumed to be a second-order nonlinear one. The nonlinearity of the medium is further assumed to be activated by an externally applied classical pump field. As a consequence, now there are <i>two</i> external controlling agents, the temperature and nonlinearity strength. We then proceed to calculate the quadrature mean values in the thermodynamical limit and for a large number of atoms as a function of temperature. An analysis of the calculated mean values, along with relevant figures, reveals temperature-dependent conditions for realizing trivial, electric, and magnetic optical phases. Moreover, we shall demonstrate that the atom-field coupling strength gives rise to two distinct regimes where the optical phases behave quite differently. In one of the two regimes it is possible for the phases to coexist, while in the other it is not. As a profound result, it is demonstrated that for such a system there can exist a unique temperature (triple point) at which the three optical phases coexist.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"32 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1103/physreva.110.032420
Dong-Dong Dong, Li-Juan Li, Xue-Ke Song, Liu Ye, Dong Wang
Although genuine multipartite entanglement (GME), as one quantum resource, is indispensable in quantum information processing, most of the existing measures cannot detect GME faithfully. In this paper we present a GME measure, namely, the minimum pairwise concurrence (MPC), by introducing pairwise entanglement, which characterizes the entanglement between two single-qubit subsystems of a multipartite system without tracing out the remaining qubit. The pairwise entanglement can be obtained by combining the entanglement of the reduced subsystem and the three-tangle. Compared with existing measures, the MPC measure outperforms the previous ones in many aspects. Due to its fine properties, it thus is believed that the MPC could be a good candidate for achieving potential quantum tasks and also could facilitate the understanding of GME.
{"title":"Quantifying genuine tripartite entanglement by reshaping the state","authors":"Dong-Dong Dong, Li-Juan Li, Xue-Ke Song, Liu Ye, Dong Wang","doi":"10.1103/physreva.110.032420","DOIUrl":"https://doi.org/10.1103/physreva.110.032420","url":null,"abstract":"Although genuine multipartite entanglement (GME), as one quantum resource, is indispensable in quantum information processing, most of the existing measures cannot detect GME faithfully. In this paper we present a GME measure, namely, the minimum pairwise concurrence (MPC), by introducing pairwise entanglement, which characterizes the entanglement between two single-qubit subsystems of a multipartite system without tracing out the remaining qubit. The pairwise entanglement can be obtained by combining the entanglement of the reduced subsystem and the three-tangle. Compared with existing measures, the MPC measure outperforms the previous ones in many aspects. Due to its fine properties, it thus is believed that the MPC could be a good candidate for achieving potential quantum tasks and also could facilitate the understanding of GME.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"27 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1103/physreva.110.033319
Yuki Nakamura, Ryui Kaneko, Ippei Danshita
Rydberg atoms in an optical tweezer array have been used as a quantum simulator of the spin- antiferromagnetic Ising model with longitudinal and transverse fields. We suggest how to implement the next-nearest-neighbor (NNN) interaction the sign of which is opposite to that of the nearest-neighbor one in the Rydberg atom systems. We show that this can be achieved by weakly coupling one Rydberg state with another Rydberg state. We further study the surface criticality associated with the first-order quantum phase transition between the antiferromagnetic and paramagnetic phases, which emerges due to the sign-inverted NNN interaction. From the microscopic model, we derive a Ginzburg-Landau (GL) equation, which describes static and dynamic properties of the antiferromagnetic order parameter near the transition. Using both analytical GL theory and numerical method based on a mean-field theory, we calculate the order parameter in the proximity of a boundary of the system in order to show that the healing length of the order parameter logarithmically diverges, signaling the surface criticality.
{"title":"Surface criticality in the mixed-field Ising model with sign-inverted next-nearest-neighbor interaction","authors":"Yuki Nakamura, Ryui Kaneko, Ippei Danshita","doi":"10.1103/physreva.110.033319","DOIUrl":"https://doi.org/10.1103/physreva.110.033319","url":null,"abstract":"Rydberg atoms in an optical tweezer array have been used as a quantum simulator of the spin-<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></math> antiferromagnetic Ising model with longitudinal and transverse fields. We suggest how to implement the next-nearest-neighbor (NNN) interaction the sign of which is opposite to that of the nearest-neighbor one in the Rydberg atom systems. We show that this can be achieved by weakly coupling one Rydberg state with another Rydberg state. We further study the surface criticality associated with the first-order quantum phase transition between the antiferromagnetic and paramagnetic phases, which emerges due to the sign-inverted NNN interaction. From the microscopic model, we derive a Ginzburg-Landau (GL) equation, which describes static and dynamic properties of the antiferromagnetic order parameter near the transition. Using both analytical GL theory and numerical method based on a mean-field theory, we calculate the order parameter in the proximity of a boundary of the system in order to show that the healing length of the order parameter logarithmically diverges, signaling the surface criticality.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"18 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-16DOI: 10.1103/physreva.110.033317
G. Bougas, G. C. Katsimiga, P. G. Kevrekidis, S. I. Mistakidis
We unravel stationary states in the form of dark soliton stripes, bubbles, and kinks embedded in a two-dimensional droplet-bearing setting emulated by an extended Gross-Pitaevskii approach. The existence of these configurations is corroborated through an effectively reduced potential picture demonstrating their concrete parametric regions of existence. The excitation spectra of such configurations are analyzed within the Bogoliubov–de Gennes framework exposing the destabilization of dark soliton stripes and bubbles, while confirming the stability of droplets, and importantly unveiling spectral stability of the kink against transverse excitations. Additionally, a variational approach is constructed providing access to the transverse stability analysis of the dark soliton stripe for arbitrary chemical potentials and widths of the structure. This is subsequently compared with the stability analysis outcome demonstrating very good agreement at small wave numbers. Dynamical destabilization of dark soliton stripes via the snake instability is showcased, while bubbles are found to feature both a splitting into a gray soliton pair and a transverse instability thereof. These results shed light on unexplored stability and instability properties of nonlinear excitations in environments featuring a competition of mean-field repulsion and beyond-mean-field attraction that can be probed by state-of-the-art experiments.
{"title":"Stability and dynamics of nonlinear excitations in a two-dimensional droplet-bearing environment","authors":"G. Bougas, G. C. Katsimiga, P. G. Kevrekidis, S. I. Mistakidis","doi":"10.1103/physreva.110.033317","DOIUrl":"https://doi.org/10.1103/physreva.110.033317","url":null,"abstract":"We unravel stationary states in the form of dark soliton stripes, bubbles, and kinks embedded in a two-dimensional droplet-bearing setting emulated by an extended Gross-Pitaevskii approach. The existence of these configurations is corroborated through an effectively reduced potential picture demonstrating their concrete parametric regions of existence. The excitation spectra of such configurations are analyzed within the Bogoliubov–de Gennes framework exposing the destabilization of dark soliton stripes and bubbles, while confirming the stability of droplets, and importantly unveiling spectral stability of the kink against transverse excitations. Additionally, a variational approach is constructed providing access to the transverse stability analysis of the dark soliton stripe for arbitrary chemical potentials and widths of the structure. This is subsequently compared with the stability analysis outcome demonstrating very good agreement at small wave numbers. Dynamical destabilization of dark soliton stripes via the snake instability is showcased, while bubbles are found to feature both a splitting into a gray soliton pair and a transverse instability thereof. These results shed light on unexplored stability and instability properties of nonlinear excitations in environments featuring a competition of mean-field repulsion and beyond-mean-field attraction that can be probed by state-of-the-art experiments.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"124 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-16DOI: 10.1103/physreva.110.033314
Vaibhav Sharma, Erich J. Mueller
We calculate the properties of a one-dimensional lattice gauge theory in different Gauss-law sectors, corresponding to different configurations of static charges, set by the orientations of the gauge spins. Importantly, in quantum simulator experiments these sectors can be accessed without adding any additional physical particles or changing the Hamiltonian: the Gauss-law sectors are simply set by the initial conditions. We study the interplay between conservation laws and interactions when the static charges are chosen to form periodic patterns. We classify the different Gauss-law sectors and use the density matrix renormalization group to calculate the ground-state compressibility, density profiles, charge-density-wave order parameters, and single-particle correlation functions as a function of matter density. We find confined and deconfined phases, charge density waves, correlated insulators, and supersolids.
{"title":"One-dimensional Z2 lattice gauge theory in periodic Gauss-law sectors","authors":"Vaibhav Sharma, Erich J. Mueller","doi":"10.1103/physreva.110.033314","DOIUrl":"https://doi.org/10.1103/physreva.110.033314","url":null,"abstract":"We calculate the properties of a one-dimensional <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Z</mi><mn>2</mn></msub></math> lattice gauge theory in different <i>Gauss-law sectors</i>, corresponding to different configurations of static charges, set by the orientations of the gauge spins. Importantly, in quantum simulator experiments these sectors can be accessed without adding any additional physical particles or changing the Hamiltonian: the Gauss-law sectors are simply set by the initial conditions. We study the interplay between conservation laws and interactions when the static charges are chosen to form periodic patterns. We classify the different Gauss-law sectors and use the density matrix renormalization group to calculate the ground-state compressibility, density profiles, charge-density-wave order parameters, and single-particle correlation functions as a function of matter density. We find confined and deconfined phases, charge density waves, correlated insulators, and supersolids.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"13 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We theoretically investigate the topological edge-state impact on high-order harmonic generation (HHG) in solids, with a focus on the modification of the topological edge-state dynamics by spatially structured (SS) light. Our findings reveal an underlying mechanism coupling the spatial inhomogeneity of light with the topological states, which leads to a notable but counterintuitive enhancement of HHG yields by SS light, even with a lower average field-intensity compared to the conventional spatially homogeneous light. We attribute this giant coupling effect to the dynamical modulation of the energy bands by the SS light in the HHG process, building an “electron lift” scenario of the topological edge states. Our study not only highlights the intricate interplay between spatial inhomogeneity of laser fields and topological condensed matter but also paves pathways for manipulating electron dynamics in solids using the unique properties of SS light.
我们从理论上研究了拓扑边缘态对固体中高阶谐波发生（HHG）的影响，重点是空间结构（SS）光对拓扑边缘态动力学的改变。我们的研究结果揭示了一种将光的空间不均匀性与拓扑态耦合起来的潜在机制，这种机制导致了空间结构光对高阶谐波发生率的显著而反直觉的增强，即使与传统的空间均匀光相比，其平均场强较低。我们将这种巨大的耦合效应归因于 HHG 过程中 SS 光对能带的动态调制，从而构建了拓扑边缘态的 "电子提升 "情景。我们的研究不仅凸显了激光场的空间不均匀性与拓扑凝聚态之间错综复杂的相互作用，还为利用 SS 光的独特性质操纵固体中的电子动力学铺平了道路。
{"title":"Enhanced high-order harmonic generation by spatially-structured-light–induced topological-edge-state dynamics","authors":"Jianghua Luo, Jiajun Xiao, Zhongwei Wu, Yang Li, Xiaosong Zhu, Yueming Zhou","doi":"10.1103/physreva.110.033111","DOIUrl":"https://doi.org/10.1103/physreva.110.033111","url":null,"abstract":"We theoretically investigate the topological edge-state impact on high-order harmonic generation (HHG) in solids, with a focus on the modification of the topological edge-state dynamics by spatially structured (SS) light. Our findings reveal an underlying mechanism coupling the spatial inhomogeneity of light with the topological states, which leads to a notable but counterintuitive enhancement of HHG yields by SS light, even with a lower average field-intensity compared to the conventional spatially homogeneous light. We attribute this giant coupling effect to the dynamical modulation of the energy bands by the SS light in the HHG process, building an “electron lift” scenario of the topological edge states. Our study not only highlights the intricate interplay between spatial inhomogeneity of laser fields and topological condensed matter but also paves pathways for manipulating electron dynamics in solids using the unique properties of SS light.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"48 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-16DOI: 10.1103/physreva.110.033109
Janine C. Franz, Stefan Yoshi Buhmann, A. Salam
In this paper we derive local-field corrections for interactions within chiral media using the Onsager real cavity model. The problem is not fully solvable analytically, so we introduce a matrix formalism to determine the correct local-field corrections. We find that left- and right-handed circularly polarized excitations yield different correction factors inside a chiral medium, analogous to their different propagation velocities. These chiral correction factors can significantly alter theoretical predictions for chiral effects within the medium. We validate our solution in various limits and special cases, particularly when the source and absorption points coincide, enabling analytical comparison for nonabsorbing media. For spontaneous emission in a chiral medium, we extend the local-field correction to absorbing media, revealing fundamentally different corrections analogous to the nonchiral case.
{"title":"Local-field corrections of the Green's tensor in chiral media","authors":"Janine C. Franz, Stefan Yoshi Buhmann, A. Salam","doi":"10.1103/physreva.110.033109","DOIUrl":"https://doi.org/10.1103/physreva.110.033109","url":null,"abstract":"In this paper we derive local-field corrections for interactions within chiral media using the Onsager real cavity model. The problem is not fully solvable analytically, so we introduce a matrix formalism to determine the correct local-field corrections. We find that left- and right-handed circularly polarized excitations yield different correction factors inside a chiral medium, analogous to their different propagation velocities. These chiral correction factors can significantly alter theoretical predictions for chiral effects within the medium. We validate our solution in various limits and special cases, particularly when the source and absorption points coincide, enabling analytical comparison for nonabsorbing media. For spontaneous emission in a chiral medium, we extend the local-field correction to absorbing media, revealing fundamentally different corrections analogous to the nonchiral case.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"4 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The quantum dense-coding (DC) protocol, which has no security feature, deals with the transmission of classical information encoded in a quantum state by using shared entanglement between a single sender and a single receiver. Its appropriate variant has been established as a quantum key distribution (QKD) scheme for shared two-qubit maximally entangled states, with the security proof utilizing the uncertainty relation of complementary observables and the Shor-Preskill entanglement purification scheme. We present the DC-based QKD protocol for higher-dimensional systems and report the lower bounds on the secret key rate, when the shared state is a two-qudit maximally entangled state, and mixtures of maximally entangled states with different ranks. The analysis also includes the impact of noisy channels on the secure key rates, before and after encoding. In both the noiseless and the noisy scenarios, we demonstrate that the key rate as well as the robustness of the protocol against noise increases with the dimension. Further, we prove that the set of useless states in the DC-based QKD protocol is convex and compact.
量子密集编码（DC）协议没有安全特性，它是通过在单个发送方和单个接收方之间使用共享纠缠来传输以量子态编码的经典信息。它的适当变体已被确立为共享双量子比特最大纠缠态的量子密钥分发（QKD）方案，其安全性证明利用了互补观测体的不确定性关系和肖-普雷斯基尔纠缠净化方案。我们提出了适用于高维系统的基于 DC 的 QKD 协议，并报告了当共享态为双量子最大纠缠态和不同等级的最大纠缠态混合物时的密钥率下限。分析还包括编码前后噪声信道对安全密钥率的影响。在无噪声和有噪声两种情况下，我们都证明了密钥速率以及协议对噪声的鲁棒性随着维度的增加而增加。此外，我们还证明了基于 DC 的 QKD 协议中的无用状态集是凸紧凑的。
{"title":"Dimensional advantage in secure information trading via the noisy dense-coding protocol","authors":"Ayan Patra, Rivu Gupta, Tamoghna Das, Aditi Sen(De)","doi":"10.1103/physreva.110.032419","DOIUrl":"https://doi.org/10.1103/physreva.110.032419","url":null,"abstract":"The quantum dense-coding (DC) protocol, which has no security feature, deals with the transmission of classical information encoded in a quantum state by using shared entanglement between a single sender and a single receiver. Its appropriate variant has been established as a quantum key distribution (QKD) scheme for shared two-qubit maximally entangled states, with the security proof utilizing the uncertainty relation of complementary observables and the Shor-Preskill entanglement purification scheme. We present the DC-based QKD protocol for higher-dimensional systems and report the lower bounds on the secret key rate, when the shared state is a two-qudit maximally entangled state, and mixtures of maximally entangled states with different ranks. The analysis also includes the impact of noisy channels on the secure key rates, before and after encoding. In both the noiseless and the noisy scenarios, we demonstrate that the key rate as well as the robustness of the protocol against noise increases with the dimension. Further, we prove that the set of useless states in the DC-based QKD protocol is convex and compact.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"18 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-16DOI: 10.1103/physreva.110.032615
Mayalakshmi Kolangatt, Anirudh Verma, Sujai Matta, Kanad Sengupta, C. M. Chandrashekar
We theoretically propose and experimentally demonstrate the use of a configurable four-qubit photonic system to generate publicly verifiable quantum random numbers, to perform entanglement verification, and to generate a secure public and private key. Quantum circuits, to generate the desired four-qubit states and its experimental realization in the photonic architecture, are carried out using photon pairs entangled in polarization and path degrees of freedom. By performing measurements on the four-qubit system and accessing partial information of the four-qubit state for public verification, we generate publicly verified and purely secured random bits at the rate of 185 kbps from collective data of 370 kbps. When the system is used for generating public and private keys, an equal number of public and private keys are generated simultaneously. We also record about 97.9% of sampled bits from four-qubit states passing entanglement verification and demonstrate the use of public and private key generated for image encryption-decryption. The theoretical model of noise on the four-qubit state and its effect on the generation rate of verified and secured bits are in perfect agreement with the experimental results. This demonstrates the practical use of the small-scale multiqubit photonic system for quantum-safe applications by providing the option for real-time verification of the security feature of the quantum system.
{"title":"Four-qubit photonic system for publicly verifiable quantum random numbers and generation of public and private key","authors":"Mayalakshmi Kolangatt, Anirudh Verma, Sujai Matta, Kanad Sengupta, C. M. Chandrashekar","doi":"10.1103/physreva.110.032615","DOIUrl":"https://doi.org/10.1103/physreva.110.032615","url":null,"abstract":"We theoretically propose and experimentally demonstrate the use of a configurable four-qubit photonic system to generate publicly verifiable quantum random numbers, to perform entanglement verification, and to generate a secure public and private key. Quantum circuits, to generate the desired four-qubit states and its experimental realization in the photonic architecture, are carried out using photon pairs entangled in polarization and path degrees of freedom. By performing measurements on the four-qubit system and accessing partial information of the four-qubit state for public verification, we generate publicly verified and purely secured random bits at the rate of 185 kbps from collective data of 370 kbps. When the system is used for generating public and private keys, an equal number of public and private keys are generated simultaneously. We also record about 97.9% of sampled bits from four-qubit states passing entanglement verification and demonstrate the use of public and private key generated for image encryption-decryption. The theoretical model of noise on the four-qubit state and its effect on the generation rate of verified and secured bits are in perfect agreement with the experimental results. This demonstrates the practical use of the small-scale multiqubit photonic system for quantum-safe applications by providing the option for real-time verification of the security feature of the quantum system.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"24 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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