Manh Tien Nguyen, Yueh-Lin Lee, D. Alfonso, Qing Shao, Yuhua Duan
CO2 capture is critical to solving global warming. Amine-based solvents are extensively used to chemically absorb CO2. Thus, it is crucial to study the chemical absorption of CO2 by amine-based solvents to better understand and optimize CO2 capture processes. Here, we use quantum computing algorithms to quantify molecular vibrational energies and reaction pathways between CO2 and a simplified amine-based solvent model—NH3. Molecular vibrational properties are important to understanding kinetics of reactions. However, the molecule size correlates with the strength of anharmonicity effect on vibrational properties, which can be challenging to address using classical computing. Quantum computing can help enhance molecular vibrational calculations by including anharmonicity. We implement a variational quantum eigensolver (VQE) algorithm in a quantum simulator to calculate ground state vibrational energies of reactants and products of the CO2 and NH3 reaction. The VQE calculations yield ground vibrational energies of CO2 and NH3 with similar accuracy to classical computing. In the presence of hardware noise, Compact Heuristic for Chemistry (CHC) ansatz with shallower circuit depth performs better than Unitary Vibrational Coupled Cluster. The “Zero Noise Extrapolation” error-mitigation approach in combination with CHC ansatz improves the vibrational calculation accuracy. Excited vibrational states are accessed with quantum equation of motion method for CO2 and NH3. Using quantum Hartree–Fock (HF) embedding algorithm to calculate electronic energies, the corresponding reaction profile compares favorably with Coupled Cluster Singles and Doubles while being more accurate than HF. Our research showcases quantum computing applications in the study of CO2 capture reactions.
二氧化碳捕获是解决全球变暖问题的关键。胺基溶剂被广泛用于化学吸收二氧化碳。因此，研究胺基溶剂对CO2的化学吸收对于更好地理解和优化CO2捕获过程至关重要。在这里，我们使用量子计算算法来量化CO2与简化胺基溶剂模型- nh3之间的分子振动能和反应途径。分子的振动性质对理解反应动力学是很重要的。然而，分子大小与振动性质的非调和效应的强度相关，这可能是使用经典计算来解决的挑战。量子计算可以通过包含非调和性来帮助增强分子振动计算。我们在量子模拟器中实现了一种变分量子特征求解(VQE)算法来计算CO2和NH3反应的反应物和生成物的基态振动能量。VQE计算得到CO2和NH3的地面振动能，其精度与经典计算相似。在存在硬件噪声的情况下，电路深度较浅的化学紧凑型启发式(Compact Heuristic for Chemistry, CHC)簇的性能优于单一振动耦合簇。“零噪声外推”误差缓解方法与CHC分析相结合，提高了振动计算精度。用量子运动方程方法得到了CO2和NH3的激发态。采用量子Hartree-Fock (HF)嵌入算法计算电子能，相应的反应谱优于偶联簇单和双反应谱，而比偶联簇双反应谱更准确。我们的研究展示了量子计算在二氧化碳捕获反应研究中的应用。
{"title":"Description of reaction and vibrational energetics of CO2–NH3 interaction using quantum computing algorithms","authors":"Manh Tien Nguyen, Yueh-Lin Lee, D. Alfonso, Qing Shao, Yuhua Duan","doi":"10.1116/5.0137750","DOIUrl":"https://doi.org/10.1116/5.0137750","url":null,"abstract":"CO2 capture is critical to solving global warming. Amine-based solvents are extensively used to chemically absorb CO2. Thus, it is crucial to study the chemical absorption of CO2 by amine-based solvents to better understand and optimize CO2 capture processes. Here, we use quantum computing algorithms to quantify molecular vibrational energies and reaction pathways between CO2 and a simplified amine-based solvent model—NH3. Molecular vibrational properties are important to understanding kinetics of reactions. However, the molecule size correlates with the strength of anharmonicity effect on vibrational properties, which can be challenging to address using classical computing. Quantum computing can help enhance molecular vibrational calculations by including anharmonicity. We implement a variational quantum eigensolver (VQE) algorithm in a quantum simulator to calculate ground state vibrational energies of reactants and products of the CO2 and NH3 reaction. The VQE calculations yield ground vibrational energies of CO2 and NH3 with similar accuracy to classical computing. In the presence of hardware noise, Compact Heuristic for Chemistry (CHC) ansatz with shallower circuit depth performs better than Unitary Vibrational Coupled Cluster. The “Zero Noise Extrapolation” error-mitigation approach in combination with CHC ansatz improves the vibrational calculation accuracy. Excited vibrational states are accessed with quantum equation of motion method for CO2 and NH3. Using quantum Hartree–Fock (HF) embedding algorithm to calculate electronic energies, the corresponding reaction profile compares favorably with Coupled Cluster Singles and Doubles while being more accurate than HF. Our research showcases quantum computing applications in the study of CO2 capture reactions.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45608836","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}
Optical splitters are one of the most important interconnects in the optical chips of future optical quantum computers. Here, we introduce novel quantum photonic splitters based on polymeric submicropillars that split the single-photon signal generated by a colloidal quantum dot (QD) into multiple outputs, which can be easily accessed through a conventional confocal scanning optical system. Using a single continuous-wave laser with a low absorption wavelength for both polymer material and QDs, we were able to first deterministically place a single-photon emitter (SPE) within one of the submicropillars and then characterize the single-photon guiding effect of the fabricated structures. The submicropillars, with their size and position which are comprehensively optimized by numerical simulations, act as single-mode directional coupler guiding both the laser excitation and the single-photon emission thanks to the evanescent wave coupling effect. With one-step fabrication, we can create a well-distributed array of “imaginary” SPEs from an original SPE. Our method opens various applications in integrated devices based on solid-state quantum emitters.
{"title":"Single-photon splitting by polymeric submicropillars structures","authors":"Gia Long Ngo, J. Hermier, N. D. Lai","doi":"10.1116/5.0135915","DOIUrl":"https://doi.org/10.1116/5.0135915","url":null,"abstract":"Optical splitters are one of the most important interconnects in the optical chips of future optical quantum computers. Here, we introduce novel quantum photonic splitters based on polymeric submicropillars that split the single-photon signal generated by a colloidal quantum dot (QD) into multiple outputs, which can be easily accessed through a conventional confocal scanning optical system. Using a single continuous-wave laser with a low absorption wavelength for both polymer material and QDs, we were able to first deterministically place a single-photon emitter (SPE) within one of the submicropillars and then characterize the single-photon guiding effect of the fabricated structures. The submicropillars, with their size and position which are comprehensively optimized by numerical simulations, act as single-mode directional coupler guiding both the laser excitation and the single-photon emission thanks to the evanescent wave coupling effect. With one-step fabrication, we can create a well-distributed array of “imaginary” SPEs from an original SPE. Our method opens various applications in integrated devices based on solid-state quantum emitters.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42750591","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}
Onur Danaci, Wenlei Zhang, R. Coleman, W. Djakam, Michaela Amoo, R. Glasser, B. Kirby, Moussa N'Gom, T. Searles
The ability to prepare systems in specific target states through quantum engineering is essential for realizing the new technologies promised by a second quantum revolution. Here, we recast the fundamental problem of state preparation in high-dimensional Hilbert spaces as ManQala, a quantum game inspired by the West African sowing game mancala. Motivated by optimal gameplay in solitaire mancala, where nested nearest-neighbor permutations and actions evolve the state of the game board to its target configuration, ManQala acts as a pre-processing approach for deterministically arranging particles in a quantum control problem. Once pre-processing with ManQala is complete, existing quantum control methods are applied, but now with a reduced search space. We find that ManQala-type strategies match, or outperform, competing approaches in terms of final state variance even in small-scale quantum state engineering problems where we expect the slightest advantage, since the relative reduction in search space is the least. These results suggest that ManQala provides a rich platform for designing control protocols relevant to quantum technologies.
{"title":"ManQala: Game-inspired strategies for quantum state engineering","authors":"Onur Danaci, Wenlei Zhang, R. Coleman, W. Djakam, Michaela Amoo, R. Glasser, B. Kirby, Moussa N'Gom, T. Searles","doi":"10.1116/5.0148240","DOIUrl":"https://doi.org/10.1116/5.0148240","url":null,"abstract":"The ability to prepare systems in specific target states through quantum engineering is essential for realizing the new technologies promised by a second quantum revolution. Here, we recast the fundamental problem of state preparation in high-dimensional Hilbert spaces as ManQala, a quantum game inspired by the West African sowing game mancala. Motivated by optimal gameplay in solitaire mancala, where nested nearest-neighbor permutations and actions evolve the state of the game board to its target configuration, ManQala acts as a pre-processing approach for deterministically arranging particles in a quantum control problem. Once pre-processing with ManQala is complete, existing quantum control methods are applied, but now with a reduced search space. We find that ManQala-type strategies match, or outperform, competing approaches in terms of final state variance even in small-scale quantum state engineering problems where we expect the slightest advantage, since the relative reduction in search space is the least. These results suggest that ManQala provides a rich platform for designing control protocols relevant to quantum technologies.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45552226","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}
D. Barker, J. Fedchak, J. Kłos, J. Scherschligt, A. A. Sheikh, E. Tiesinga, S. Eckel
We present the measurements of thermalized collisional rate coefficients for ultra-cold 7Li and 87Rb colliding with room-temperature He, Ne, N2, Ar, Kr, and Xe. In our experiments, a combined flowmeter and dynamic expansion system, a vacuum metrology standard, is used to set a known number density for the room-temperature background gas in the vicinity of the magnetically trapped 7Li or 87Rb clouds. Each collision with a background atom or molecule removes a 7Li or 87Rb atom from its trap, and the change in the atom loss rate with background gas density is used to determine the thermalized loss rate coefficients with fractional standard uncertainties better than 1.6% for 7Li and 2.7% for 87Rb. We find consistency—a degree of equivalence of less than one—between the measurements and recent quantum-scattering calculations of the loss rate coefficients [Kłos and Tiesinga, J. Chem. Phys. 158, 014308 (2023)], with the exception of the loss rate coefficient for both 7Li and 87Rb colliding with Ar. Nevertheless, the agreement between theory and experiment for all other studied systems provides validation that a quantum-based measurement of vacuum pressure using cold atoms also serves as a primary standard for vacuum pressure, which we refer to as the cold-atom vacuum standard.
我们给出了超冷7Li和87Rb与室温He, Ne, N2, Ar, Kr和Xe碰撞的热化碰撞速率系数的测量结果。在我们的实验中，我们使用一个组合流量计和动态膨胀系统，一个真空计量标准，来设定一个已知的数字密度在室温背景气体附近的磁捕获7Li或87Rb云。每次与背景原子或分子的碰撞都会使7Li或87Rb原子从其陷阱中移除，原子损失率随背景气体密度的变化用于确定热化损失率系数，其分数标准不确定度优于7Li的1.6%和87Rb的2.7%。我们在测量结果和最近的损失率系数的量子散射计算[Kłos和Tiesinga, J. Chem]之间发现了一致性——小于1的等效程度。物理学报，158,014308(2023)]，除了7Li和87Rb与Ar碰撞的损失率系数。然而，所有其他研究系统的理论和实验之间的一致性提供了验证，即使用冷原子对真空压力的基于量子的测量也可以作为真空压力的主要标准，我们称之为冷原子真空标准。
{"title":"Accurate measurement of the loss rate of cold atoms due to background gas collisions for the quantum-based cold atom vacuum standard","authors":"D. Barker, J. Fedchak, J. Kłos, J. Scherschligt, A. A. Sheikh, E. Tiesinga, S. Eckel","doi":"10.1116/5.0147686","DOIUrl":"https://doi.org/10.1116/5.0147686","url":null,"abstract":"We present the measurements of thermalized collisional rate coefficients for ultra-cold 7Li and 87Rb colliding with room-temperature He, Ne, N2, Ar, Kr, and Xe. In our experiments, a combined flowmeter and dynamic expansion system, a vacuum metrology standard, is used to set a known number density for the room-temperature background gas in the vicinity of the magnetically trapped 7Li or 87Rb clouds. Each collision with a background atom or molecule removes a 7Li or 87Rb atom from its trap, and the change in the atom loss rate with background gas density is used to determine the thermalized loss rate coefficients with fractional standard uncertainties better than 1.6% for 7Li and 2.7% for 87Rb. We find consistency—a degree of equivalence of less than one—between the measurements and recent quantum-scattering calculations of the loss rate coefficients [Kłos and Tiesinga, J. Chem. Phys. 158, 014308 (2023)], with the exception of the loss rate coefficient for both 7Li and 87Rb colliding with Ar. Nevertheless, the agreement between theory and experiment for all other studied systems provides validation that a quantum-based measurement of vacuum pressure using cold atoms also serves as a primary standard for vacuum pressure, which we refer to as the cold-atom vacuum standard.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47392600","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 address routing of classical and quantum information over quantum network and show how to exploit chirality (directionality) to achieve nearly optimal and robust transport. In particular, we prove how continuous-time chiral quantum walks over a minimal graph are able to model directional transfer of information over a network. At first, we show how classical information, encoded onto an excitation localized at one vertex of a simple graph, may be sent to any other chosen location with nearly unit fidelity by tuning a single phase. Then, we prove that high-fidelity transport is also possible for coherent superpositions of states, i.e., for routing of quantum information. Furthermore, we show that by tuning the phase parameter, one obtains universal quantum routing, i.e., independent on the input state. In our scheme, chirality is governed by a single phase, and the routing probability is robust against fluctuations of this parameter. Finally, we address characterization of quantum routers and show how to exploit the self-energies of the graph to achieve high precision in estimating the phase parameter.
{"title":"Quantum routing of information using chiral quantum walks","authors":"Alberto Bottarelli, Massimo Frigerio, M. Paris","doi":"10.1116/5.0146805","DOIUrl":"https://doi.org/10.1116/5.0146805","url":null,"abstract":"We address routing of classical and quantum information over quantum network and show how to exploit chirality (directionality) to achieve nearly optimal and robust transport. In particular, we prove how continuous-time chiral quantum walks over a minimal graph are able to model directional transfer of information over a network. At first, we show how classical information, encoded onto an excitation localized at one vertex of a simple graph, may be sent to any other chosen location with nearly unit fidelity by tuning a single phase. Then, we prove that high-fidelity transport is also possible for coherent superpositions of states, i.e., for routing of quantum information. Furthermore, we show that by tuning the phase parameter, one obtains universal quantum routing, i.e., independent on the input state. In our scheme, chirality is governed by a single phase, and the routing probability is robust against fluctuations of this parameter. Finally, we address characterization of quantum routers and show how to exploit the self-energies of the graph to achieve high precision in estimating the phase parameter.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44639164","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}
C. Barenghi, H. Middleton-Spencer, L. Galantucci, N. Parker
We collect and describe the observed geometrical and dynamical properties of turbulence in quantum fluids, particularly superfluid helium and atomic condensates for which more information about turbulence is available. Considering the spectral features, the temporal decay, and the comparison with relevant turbulent classical flows, we identify three main limiting types of quantum turbulence: Kolmogorov quantum turbulence, Vinen quantum turbulence, and strong quantum turbulence. This classification will be useful to analyze and interpret new results in these and other quantum fluids.
{"title":"Types of quantum turbulence","authors":"C. Barenghi, H. Middleton-Spencer, L. Galantucci, N. Parker","doi":"10.1116/5.0146107","DOIUrl":"https://doi.org/10.1116/5.0146107","url":null,"abstract":"We collect and describe the observed geometrical and dynamical properties of turbulence in quantum fluids, particularly superfluid helium and atomic condensates for which more information about turbulence is available. Considering the spectral features, the temporal decay, and the comparison with relevant turbulent classical flows, we identify three main limiting types of quantum turbulence: Kolmogorov quantum turbulence, Vinen quantum turbulence, and strong quantum turbulence. This classification will be useful to analyze and interpret new results in these and other quantum fluids.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44668139","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}
Quantum metrology and quantum communications are typically considered as distinct applications in the broader portfolio of quantum technologies. However, there are cases where we might want to combine the two, and recent proposals have shown how this might be achieved in entanglement-based systems. Here, we present an entanglement-free alternative that has advantages in terms of simplicity and practicality, requiring only individual qubits to be transmitted. We demonstrate the performance of the scheme in both the low and high data limits, showing quantum advantages both in terms of measurement precision and security against a range of possible attacks.
{"title":"Secure quantum remote sensing without entanglement","authors":"S. Moore, J. Dunningham","doi":"10.1116/5.0137260","DOIUrl":"https://doi.org/10.1116/5.0137260","url":null,"abstract":"Quantum metrology and quantum communications are typically considered as distinct applications in the broader portfolio of quantum technologies. However, there are cases where we might want to combine the two, and recent proposals have shown how this might be achieved in entanglement-based systems. Here, we present an entanglement-free alternative that has advantages in terms of simplicity and practicality, requiring only individual qubits to be transmitted. We demonstrate the performance of the scheme in both the low and high data limits, showing quantum advantages both in terms of measurement precision and security against a range of possible attacks.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49606114","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}
Despite its indisputable merits, the Wigner phase-space formulation has not been widely explored for systems with SU(1,1) symmetry, as a simple operational definition of the Wigner function has proved elusive in this case. We capitalize on unique properties of the parity operator, to derive in a consistent way a bona fide SU(1,1) Wigner function that faithfully parallels the structure of its continuous-variable counterpart. We propose an optical scheme, involving a squeezer and photon-number-resolving detectors, that allows for direct point-by-point sampling of that Wigner function. This provides an adequate framework to represent SU(1,1) states satisfactorily.
{"title":"Local sampling of the SU(1,1) Wigner function","authors":"N. Fabre, A. Klimov, G. Leuchs, L. Sánchez‐Soto","doi":"10.1116/5.0134784","DOIUrl":"https://doi.org/10.1116/5.0134784","url":null,"abstract":"Despite its indisputable merits, the Wigner phase-space formulation has not been widely explored for systems with SU(1,1) symmetry, as a simple operational definition of the Wigner function has proved elusive in this case. We capitalize on unique properties of the parity operator, to derive in a consistent way a bona fide SU(1,1) Wigner function that faithfully parallels the structure of its continuous-variable counterpart. We propose an optical scheme, involving a squeezer and photon-number-resolving detectors, that allows for direct point-by-point sampling of that Wigner function. This provides an adequate framework to represent SU(1,1) states satisfactorily.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43679284","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}
E. Ilo-Okeke, Ping Chen, Shuang Li, B. C. Anusionwu, V. Ivannikov, T. Byrnes
We derive a measurement operator corresponding to a quantum nondemolition (QND) measurement of an atomic ensemble. The quantum measurement operator takes the form of a positive operator valued measure (POVM) and is valid for arbitrary interaction times, initial coherent state amplitudes, and final photon measurement outcomes. We analyze the dependence on various parameters and show that the effect of the QND measurement for short interaction times is to apply a Gaussian modulation of the initial state wavefunction. We derive approximate expressions for the POVM in various limits, such as the short interaction time regime and projective measurement limit. Several examples are shown, which show how spin squeezing and Schrodinger cat states can be generated using the measurement.
{"title":"Measurement operator for quantum nondemolition measurements","authors":"E. Ilo-Okeke, Ping Chen, Shuang Li, B. C. Anusionwu, V. Ivannikov, T. Byrnes","doi":"10.1116/5.0141921","DOIUrl":"https://doi.org/10.1116/5.0141921","url":null,"abstract":"We derive a measurement operator corresponding to a quantum nondemolition (QND) measurement of an atomic ensemble. The quantum measurement operator takes the form of a positive operator valued measure (POVM) and is valid for arbitrary interaction times, initial coherent state amplitudes, and final photon measurement outcomes. We analyze the dependence on various parameters and show that the effect of the QND measurement for short interaction times is to apply a Gaussian modulation of the initial state wavefunction. We derive approximate expressions for the POVM in various limits, such as the short interaction time regime and projective measurement limit. Several examples are shown, which show how spin squeezing and Schrodinger cat states can be generated using the measurement.","PeriodicalId":93525,"journal":{"name":"AVS quantum science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46909519","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}
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}
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