Benjamin Collis, Saahil Patel, Daniel Koch, Massimiliano Cutugno, L. Wessing, P. Alsing
We develop and implement two realizations of quantum graph neural networks (QGNN), applied to the task of particle interaction simulation. The first QGNN is a speculative quantum-classical hybrid learning model that relies on the ability to directly utilize superposition states as classical information to propagate information between particles. The second is an implementable quantum-classical hybrid learning model that propagates particle information directly through the parameters of RX rotation gates. A classical graph neural network (CGNN) is also trained in the same task. Both the Speculative QGNN and CGNN act as controls against the Implementable QGNN. Comparison between classical and quantum models is based on the loss value and accuracy of each model. Overall, each model had a high learning efficiency, in which the loss value rapidly approached zero during training; however, each model was moderately inaccurate. Comparing performances, our results show that the Implementable QGNN has a potential advantage over the CGNN. Additionally, we show that a slight alteration in hyperparameters in the CGNN notably improves accuracy, suggesting that further fine tuning could mitigate the issue of moderate inaccuracy in each model.
{"title":"Physics simulation via quantum graph neural network","authors":"Benjamin Collis, Saahil Patel, Daniel Koch, Massimiliano Cutugno, L. Wessing, P. Alsing","doi":"10.1116/5.0145722","DOIUrl":"https://doi.org/10.1116/5.0145722","url":null,"abstract":"We develop and implement two realizations of quantum graph neural networks (QGNN), applied to the task of particle interaction simulation. The first QGNN is a speculative quantum-classical hybrid learning model that relies on the ability to directly utilize superposition states as classical information to propagate information between particles. The second is an implementable quantum-classical hybrid learning model that propagates particle information directly through the parameters of RX rotation gates. A classical graph neural network (CGNN) is also trained in the same task. Both the Speculative QGNN and CGNN act as controls against the Implementable QGNN. Comparison between classical and quantum models is based on the loss value and accuracy of each model. Overall, each model had a high learning efficiency, in which the loss value rapidly approached zero during training; however, each model was moderately inaccurate. Comparing performances, our results show that the Implementable QGNN has a potential advantage over the CGNN. Additionally, we show that a slight alteration in hyperparameters in the CGNN notably improves accuracy, suggesting that further fine tuning could mitigate the issue of moderate inaccuracy in each model.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":"42 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41261828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Light detection and ranging is a key technology for a number of applications, from relatively simple distance ranging to environmental monitoring. When dealing with low photon numbers, an important issue is the improvement of the signal-to-noise-ratio, which is severely affected by external sources whose emission is captured by the detection apparatus. In this paper, we present an extension of the technique developed in Cohen et al. [Phys. Rev. Lett. 123, 203601 (2019)] to the effects caused by the propagation of light through a turbulent media as well as the detection through photon counting devices bearing imperfections in terms of efficiency and number resolution. Our results indicate that even less performing technology can result in a useful detection scheme.
{"title":"Thresholded quantum LIDAR in turbolent media","authors":"Walter Zedda, I. Gianani, V. Berardi, M. Barbieri","doi":"10.1116/5.0107125","DOIUrl":"https://doi.org/10.1116/5.0107125","url":null,"abstract":"Light detection and ranging is a key technology for a number of applications, from relatively simple distance ranging to environmental monitoring. When dealing with low photon numbers, an important issue is the improvement of the signal-to-noise-ratio, which is severely affected by external sources whose emission is captured by the detection apparatus. In this paper, we present an extension of the technique developed in Cohen et al. [Phys. Rev. Lett. 123, 203601 (2019)] to the effects caused by the propagation of light through a turbulent media as well as the detection through photon counting devices bearing imperfections in terms of efficiency and number resolution. Our results indicate that even less performing technology can result in a useful detection scheme.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48652637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Macrorealism is a characteristic feature of many, but not all, classical systems. It is known, for example, that classical light can violate a Leggett–Garg inequality and, hence, reject a macrorealist interpretation. A recent experiment has used entangled light and negative measurements to demonstrate a loophole-free test of macrorealism [Joarder et al., PRX Quantum 3, 010307 (2022)]. This paper shows that such an experiment, while soundly rejecting macrorealism, may nevertheless be open to a classical interpretation. This is done by offering an explicit classical model of heralded photon detection in an optical interferometer with beam blockers. A numerical analysis of the model shows good agreement with experimental observations and consistency with both local realism and a rejection of macrorealism.
{"title":"Classical model of quantum interferometry tests of macrorealism","authors":"B. L. La Cour","doi":"10.1116/5.0131209","DOIUrl":"https://doi.org/10.1116/5.0131209","url":null,"abstract":"Macrorealism is a characteristic feature of many, but not all, classical systems. It is known, for example, that classical light can violate a Leggett–Garg inequality and, hence, reject a macrorealist interpretation. A recent experiment has used entangled light and negative measurements to demonstrate a loophole-free test of macrorealism [Joarder et al., PRX Quantum 3, 010307 (2022)]. This paper shows that such an experiment, while soundly rejecting macrorealism, may nevertheless be open to a classical interpretation. This is done by offering an explicit classical model of heralded photon detection in an optical interferometer with beam blockers. A numerical analysis of the model shows good agreement with experimental observations and consistency with both local realism and a rejection of macrorealism.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48423959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
By adopting the variational quantum simulator method on noisy quantum computers, we simulate the temporal evolution of the population transfer in a laser-driven three-level system, representing [Formula: see text] suddenly exposed to an intense laser field. We have conducted experiments using an IBM Quantum computer. In order to mitigate the error caused by the execution of the Hadamard test circuits, the Clifford data regression method is adopted. The characteristic features in the temporal evolution of the population transfer, leading to the population inversion and the air lasing, have been well reproduced.
{"title":"Simulation of a laser-driven three-level system by a noisy quantum computer","authors":"T. Nishi, E. Lötstedt, K. Yamanouchi","doi":"10.1116/5.0098614","DOIUrl":"https://doi.org/10.1116/5.0098614","url":null,"abstract":"By adopting the variational quantum simulator method on noisy quantum computers, we simulate the temporal evolution of the population transfer in a laser-driven three-level system, representing [Formula: see text] suddenly exposed to an intense laser field. We have conducted experiments using an IBM Quantum computer. In order to mitigate the error caused by the execution of the Hadamard test circuits, the Clifford data regression method is adopted. The characteristic features in the temporal evolution of the population transfer, leading to the population inversion and the air lasing, have been well reproduced.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42883537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A common type of weak-value experiment prepares a single particle in one state, weakly measures the occupation number of another state, and post-selects on finding the particle in a third state (a “click”). Most weak-value experiments have been done with photons, but the heralded preparation of a single photon is difficult and slow of rate. Here, we show that the weak value mentioned above can be measured using strong (many-photon) coherent states, while still needing only a click detector such as an avalanche photodiode. One simply subtracts the no-click weak value from the click weak-value and scales the answer by a simple function of the click probability.
{"title":"Obtaining a single-photon weak value from experiments using a strong (many-photon) coherent state","authors":"H. Wiseman, Aephraim M. Steinberg, M. Hallaji","doi":"10.1116/5.0137579","DOIUrl":"https://doi.org/10.1116/5.0137579","url":null,"abstract":"A common type of weak-value experiment prepares a single particle in one state, weakly measures the occupation number of another state, and post-selects on finding the particle in a third state (a “click”). Most weak-value experiments have been done with photons, but the heralded preparation of a single photon is difficult and slow of rate. Here, we show that the weak value mentioned above can be measured using strong (many-photon) coherent states, while still needing only a click detector such as an avalanche photodiode. One simply subtracts the no-click weak value from the click weak-value and scales the answer by a simple function of the click probability.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46757085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article explores the dynamics of many-body atomic systems symmetrically coupled to Lorentzian photonic cavity systems. Our study reveals interesting dynamical characteristics, including non-zero steady states, super-radiant decay, enhanced energy transfer, and the ability to modulate oscillations in the atomic system by tuning environmental degrees of freedom. We also analyze a configuration consisting of a three-atom chain embedded in a photonic cavity. Similarly, we find a strong enhancement of the energy transfer rate between the two ends of the chain and identified specific initial conditions that lead to significantly reduced dissipation between the two atoms at the end of the chain. Another configuration of interest consists of two symmetrical detuned reservoirs with respect to the atomic system. In the single atom case, we show that it is possible to enhance the decay rate of the system by modulating its reservoir detuning. In contrast, in the many-atom case, this results in dynamics akin to the on-resonant cavity. Finally, we examine the validity of the rotating wave approximation through a direct comparison against the numerically exact hierarchical equations of motion. We find good agreement in the weak coupling regime, while in the intermediate coupling regime, we identify qualitative similarities, but the rotating wave approximation becomes less reliable. In the moderate coupling regime, we find deviations of the steady states due to the formation of mixed photon-atom states.
{"title":"Quantum memory effects in atomic ensembles coupled to photonic cavities","authors":"Adam Burgess, Marian Florescu","doi":"10.1116/5.0137078","DOIUrl":"https://doi.org/10.1116/5.0137078","url":null,"abstract":"This article explores the dynamics of many-body atomic systems symmetrically coupled to Lorentzian photonic cavity systems. Our study reveals interesting dynamical characteristics, including non-zero steady states, super-radiant decay, enhanced energy transfer, and the ability to modulate oscillations in the atomic system by tuning environmental degrees of freedom. We also analyze a configuration consisting of a three-atom chain embedded in a photonic cavity. Similarly, we find a strong enhancement of the energy transfer rate between the two ends of the chain and identified specific initial conditions that lead to significantly reduced dissipation between the two atoms at the end of the chain. Another configuration of interest consists of two symmetrical detuned reservoirs with respect to the atomic system. In the single atom case, we show that it is possible to enhance the decay rate of the system by modulating its reservoir detuning. In contrast, in the many-atom case, this results in dynamics akin to the on-resonant cavity. Finally, we examine the validity of the rotating wave approximation through a direct comparison against the numerically exact hierarchical equations of motion. We find good agreement in the weak coupling regime, while in the intermediate coupling regime, we identify qualitative similarities, but the rotating wave approximation becomes less reliable. In the moderate coupling regime, we find deviations of the steady states due to the formation of mixed photon-atom states.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63540735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The characterization of the Hamiltonian parameters defining a quantum walk is of paramount importance when performing a variety of tasks, from quantum communication to computation. When dealing with physical implementations of quantum walks, the parameters themselves may not be directly accessible, and, thus, it is necessary to find alternative estimation strategies exploiting other observables. Here, we perform the multiparameter estimation of the Hamiltonian parameters characterizing a continuous-time quantum walk over a line graph with n-neighbor interactions using a deep neural network model fed with experimental probabilities at a given evolution time. We compare our results with the bounds derived from estimation theory and find that the neural network acts as a nearly optimal estimator both when the estimation of two or three parameters is performed.
{"title":"Multiparameter estimation of continuous-time quantum walk Hamiltonians through machine learning","authors":"I. Gianani, C. Benedetti","doi":"10.1116/5.0137398","DOIUrl":"https://doi.org/10.1116/5.0137398","url":null,"abstract":"The characterization of the Hamiltonian parameters defining a quantum walk is of paramount importance when performing a variety of tasks, from quantum communication to computation. When dealing with physical implementations of quantum walks, the parameters themselves may not be directly accessible, and, thus, it is necessary to find alternative estimation strategies exploiting other observables. Here, we perform the multiparameter estimation of the Hamiltonian parameters characterizing a continuous-time quantum walk over a line graph with n-neighbor interactions using a deep neural network model fed with experimental probabilities at a given evolution time. We compare our results with the bounds derived from estimation theory and find that the neural network acts as a nearly optimal estimator both when the estimation of two or three parameters is performed.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47943347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bidirectional quantum teleportation is a fundamental protocol for exchanging quantum information between two parties. Specifically, two individuals make use of a shared resource state as well as local operations and classical communication (LOCC) to swap quantum states. In this work, we concisely highlight the contributions of our companion paper [A. U. Siddiqui and M. M. Wilde, arXiv:2010.07905 (2020)]. We develop two different ways of quantifying the error of nonideal bidirectional teleportation by means of the normalized diamond distance and the channel infidelity. We then establish that the values given by both metrics are equal for this task. Additionally, by relaxing the set of operations allowed from LOCC to those that completely preserve the positivity of the partial transpose, we obtain semidefinite programing lower bounds on the error of nonideal bidirectional teleportation. We evaluate these bounds for some key examples—isotropic states and when there is no resource state at all. In both cases, we find an analytical solution. The second example establishes a benchmark for classical versus quantum bidirectional teleportation. Another example that we investigate consists of two Bell states that have been sent through a generalized amplitude damping channel. For this scenario, we find an analytical expression for the error, as well as a numerical solution that agrees with the former up to numerical precision.
{"title":"The SWAP imposter: Bidirectional quantum teleportation and its performance","authors":"Aliza U. Siddiqui, M. Wilde","doi":"10.1116/5.0135467","DOIUrl":"https://doi.org/10.1116/5.0135467","url":null,"abstract":"Bidirectional quantum teleportation is a fundamental protocol for exchanging quantum information between two parties. Specifically, two individuals make use of a shared resource state as well as local operations and classical communication (LOCC) to swap quantum states. In this work, we concisely highlight the contributions of our companion paper [A. U. Siddiqui and M. M. Wilde, arXiv:2010.07905 (2020)]. We develop two different ways of quantifying the error of nonideal bidirectional teleportation by means of the normalized diamond distance and the channel infidelity. We then establish that the values given by both metrics are equal for this task. Additionally, by relaxing the set of operations allowed from LOCC to those that completely preserve the positivity of the partial transpose, we obtain semidefinite programing lower bounds on the error of nonideal bidirectional teleportation. We evaluate these bounds for some key examples—isotropic states and when there is no resource state at all. In both cases, we find an analytical solution. The second example establishes a benchmark for classical versus quantum bidirectional teleportation. Another example that we investigate consists of two Bell states that have been sent through a generalized amplitude damping channel. For this scenario, we find an analytical expression for the error, as well as a numerical solution that agrees with the former up to numerical precision.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48326191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We study how variations in pump brightness, for identical profiles, affect the temporal-mode structure of squeezed states generated by three different waveguided sources. Double-pass structures give optimal results in terms of indistinguishability and spectral purity.
{"title":"Waveguided sources of consistent, single-temporal-mode squeezed light: the good, the bad, and the ugly","authors":"M. Houde, N. Quesada","doi":"10.1116/5.0133009","DOIUrl":"https://doi.org/10.1116/5.0133009","url":null,"abstract":"We study how variations in pump brightness, for identical profiles, affect the temporal-mode structure of squeezed states generated by three different waveguided sources. Double-pass structures give optimal results in terms of indistinguishability and spectral purity.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":"1 1","pages":"1-3"},"PeriodicalIF":0.0,"publicationDate":"2022-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63540722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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