Dense Wavelength Division Multiplexing (DWDM) is a key technology for realizing high-capacity and flexible quantum communication networks. In addition, to realize the emerging quantum internet, quantum frequency conversion is also essential for bridging different quantum systems over optical fiber networks. In this work, we demonstrate a channel-selective quantum frequency conversion (CS-QFC), which allows active selection of the frequency of the converted photon from multiple DWDM channels. The 2.5 THz bandwidth of our CS-QFC system shows the ability to establish a 100-ch DWDM dynamic link from a single quantum system. It promises to increase the diversity of the quantum network.
{"title":"1xN DWDM channel selective quantum frequency conversion","authors":"Tomoaki Arizono, Toshiki Kobayashi, Shigehito Miki, Hirotaka Terai, Tsuyoshi Kodama, Hideki Shimoi, Takashi Yamamoto, Rikizo Ikuta","doi":"arxiv-2409.08025","DOIUrl":"https://doi.org/arxiv-2409.08025","url":null,"abstract":"Dense Wavelength Division Multiplexing (DWDM) is a key technology for\u0000realizing high-capacity and flexible quantum communication networks. In\u0000addition, to realize the emerging quantum internet, quantum frequency\u0000conversion is also essential for bridging different quantum systems over\u0000optical fiber networks. In this work, we demonstrate a channel-selective\u0000quantum frequency conversion (CS-QFC), which allows active selection of the\u0000frequency of the converted photon from multiple DWDM channels. The 2.5 THz\u0000bandwidth of our CS-QFC system shows the ability to establish a 100-ch DWDM\u0000dynamic link from a single quantum system. It promises to increase the\u0000diversity of the quantum network.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202249","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}
Oğuzcan Kırmemiş, Francisco Romão, Emmanouil Giortamis, Pramod Bhatotia
While the prominent quantum computing architectures are based on superconducting technology, new quantum hardware technologies are emerging, such as Trapped Ions, Neutral Atoms (or FPQAs), Silicon Spin Qubits, etc. This diverse set of technologies presents fundamental trade-offs in terms of scalability, performance, manufacturing, and operating expenses. To manage these diverse quantum technologies, there is a growing need for a retargetable compiler that can efficiently adapt existing code to these emerging hardware platforms. Such a retargetable compiler must be extensible to support new and rapidly evolving technologies, performant with fast compilation times and high-fidelity execution, and verifiable through rigorous equivalence checking to ensure the functional equivalence of the retargeted code. To this end, we present $Weaver$, the first extensible, performant, and verifiable retargetable quantum compiler framework with a focus on FPQAs due to their unique, promising features. $Weaver$ introduces WQASM, the first formal extension of the standard OpenQASM quantum assembly with FPQA-specific instructions to support their distinct capabilities. Next, $Weaver$ implements the WOptimizer, an extensible set of FPQA-specific optimization passes to improve execution quality. Last, the WChecker automatically checks for equivalence between the original and the retargeted code. Our evaluation shows that $Weaver$ improves compilation times by $10^3times$, execution times by $4.4times$, and execution fidelity by $10%$, on average, compared to superconducting and state-of-the-art (non-retargetable) FPQA compilers.
{"title":"Weaver: A Retargetable Compiler Framework for FPQA Quantum Architectures","authors":"Oğuzcan Kırmemiş, Francisco Romão, Emmanouil Giortamis, Pramod Bhatotia","doi":"arxiv-2409.07870","DOIUrl":"https://doi.org/arxiv-2409.07870","url":null,"abstract":"While the prominent quantum computing architectures are based on\u0000superconducting technology, new quantum hardware technologies are emerging,\u0000such as Trapped Ions, Neutral Atoms (or FPQAs), Silicon Spin Qubits, etc. This\u0000diverse set of technologies presents fundamental trade-offs in terms of\u0000scalability, performance, manufacturing, and operating expenses. To manage\u0000these diverse quantum technologies, there is a growing need for a retargetable\u0000compiler that can efficiently adapt existing code to these emerging hardware\u0000platforms. Such a retargetable compiler must be extensible to support new and\u0000rapidly evolving technologies, performant with fast compilation times and\u0000high-fidelity execution, and verifiable through rigorous equivalence checking\u0000to ensure the functional equivalence of the retargeted code. To this end, we present $Weaver$, the first extensible, performant, and\u0000verifiable retargetable quantum compiler framework with a focus on FPQAs due to\u0000their unique, promising features. $Weaver$ introduces WQASM, the first formal\u0000extension of the standard OpenQASM quantum assembly with FPQA-specific\u0000instructions to support their distinct capabilities. Next, $Weaver$ implements\u0000the WOptimizer, an extensible set of FPQA-specific optimization passes to\u0000improve execution quality. Last, the WChecker automatically checks for\u0000equivalence between the original and the retargeted code. Our evaluation shows\u0000that $Weaver$ improves compilation times by $10^3times$, execution times by\u0000$4.4times$, and execution fidelity by $10%$, on average, compared to\u0000superconducting and state-of-the-art (non-retargetable) FPQA compilers.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202260","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}
Neural networks have emerged as a promising paradigm for quantum information processing, yet they confront the challenge of generating training datasets with sufficient size and rich diversity, which is particularly acute when dealing with multipartite quantum systems. For instance, in the task of classifying different structures of multipartite entanglement in continuous variable systems, it is necessary to simulate a large number of infinite-dimension state data that can cover as many types of non-Gaussian states as possible. Here, we develop a data-augmented neural network to complete this task with homodyne measurement data. A quantum data augmentation method based on classical data processing techniques and quantum physical principles is proposed to efficiently enhance the network performance. By testing on randomly generated tripartite and quadripartite states, we demonstrate that the network can indicate the entanglement structure among the various partitions and the accuracies are significantly improved with data augmentation. Our approach allows us to further extend the use of data-driven machine learning techniques to more complex tasks of learning quantum systems encoded in a large Hilbert space.
{"title":"Classifying Multipartite Continuous Variable Entanglement Structures through Data-augmented Neural Networks","authors":"Xiaoting Gao, Mingsheng Tian, Feng-Xiao Sun, Ya-Dong Wu, Yu Xiang, Qiongyi He","doi":"arxiv-2409.07909","DOIUrl":"https://doi.org/arxiv-2409.07909","url":null,"abstract":"Neural networks have emerged as a promising paradigm for quantum information\u0000processing, yet they confront the challenge of generating training datasets\u0000with sufficient size and rich diversity, which is particularly acute when\u0000dealing with multipartite quantum systems. For instance, in the task of\u0000classifying different structures of multipartite entanglement in continuous\u0000variable systems, it is necessary to simulate a large number of\u0000infinite-dimension state data that can cover as many types of non-Gaussian\u0000states as possible. Here, we develop a data-augmented neural network to\u0000complete this task with homodyne measurement data. A quantum data augmentation\u0000method based on classical data processing techniques and quantum physical\u0000principles is proposed to efficiently enhance the network performance. By\u0000testing on randomly generated tripartite and quadripartite states, we\u0000demonstrate that the network can indicate the entanglement structure among the\u0000various partitions and the accuracies are significantly improved with data\u0000augmentation. Our approach allows us to further extend the use of data-driven\u0000machine learning techniques to more complex tasks of learning quantum systems\u0000encoded in a large Hilbert space.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202247","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}
Yoad Ordan, Yuval Bloom, Tamar Levin, Kfir Sulimany, Jennifer A. Hollingsworth, Ronen Rapaport
The original proposal of quantum key distribution (QKD) was based on ideal single photon sources, which 40 years later, are still challenging to develop. Therefore, the development of decoy state protocols using weak coherent states (WCS) from lasers, set the frontier in terms of secure key rates. Here, we propose and experimentally emulate two simple-to-implement protocols that allow practical, far from ideal sub-Poissonian photon sources to outperform state-of-the-art WCS. By engineering the photon statistics of a quantum dot's biexciton-exciton cascade, we show that either a truncated decoy state protocol or a heralded purification protocol can be employed to achieve a significantly increased performance in terms of the maximal allowed channel loss for secure key creation, which can exceed that of WCS by more than 3dB. We then show that our recently demonstrated room temperature single photon sources, based on giant colloidal quantum dots coupled to nano-antennas, are already well within the optimal performance range. These protocols can be utilized efficiently on a host of various sub-Poissonian quantum emitters having controllable photon statistics, offering a practical approach to QKD without the hindering requirements on the single photon purity of the photon source.
{"title":"Superior decoy state and purification quantum key distribution protocols for realistic quantum-dot based single photon sources","authors":"Yoad Ordan, Yuval Bloom, Tamar Levin, Kfir Sulimany, Jennifer A. Hollingsworth, Ronen Rapaport","doi":"arxiv-2409.07939","DOIUrl":"https://doi.org/arxiv-2409.07939","url":null,"abstract":"The original proposal of quantum key distribution (QKD) was based on ideal\u0000single photon sources, which 40 years later, are still challenging to develop.\u0000Therefore, the development of decoy state protocols using weak coherent states\u0000(WCS) from lasers, set the frontier in terms of secure key rates. Here, we\u0000propose and experimentally emulate two simple-to-implement protocols that allow\u0000practical, far from ideal sub-Poissonian photon sources to outperform\u0000state-of-the-art WCS. By engineering the photon statistics of a quantum dot's\u0000biexciton-exciton cascade, we show that either a truncated decoy state protocol\u0000or a heralded purification protocol can be employed to achieve a significantly\u0000increased performance in terms of the maximal allowed channel loss for secure\u0000key creation, which can exceed that of WCS by more than 3dB. We then show that\u0000our recently demonstrated room temperature single photon sources, based on\u0000giant colloidal quantum dots coupled to nano-antennas, are already well within\u0000the optimal performance range. These protocols can be utilized efficiently on a\u0000host of various sub-Poissonian quantum emitters having controllable photon\u0000statistics, offering a practical approach to QKD without the hindering\u0000requirements on the single photon purity of the photon source.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202277","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}
In the pursuit of scalable and fault-tolerant quantum computing architectures, photonic-based quantum computers have emerged as a leading frontier. This article provides a comprehensive overview of advancements in photonic quantum computing, developed by leading industry players, examining current performance, architectural designs, and strategies for developing large-scale, fault-tolerant photonic quantum computers. It also highlights recent groundbreaking experiments that leverage the unique advantages of photonic technologies, underscoring their transformative potential. This review captures a pivotal moment of photonic quantum computing in the noisy intermediate-scale quantum (NISQ) era, offering insights into how photonic quantum computers might reshape the future of quantum computing.
{"title":"Photonic Quantum Computers","authors":"M. AbuGhanem","doi":"arxiv-2409.08229","DOIUrl":"https://doi.org/arxiv-2409.08229","url":null,"abstract":"In the pursuit of scalable and fault-tolerant quantum computing\u0000architectures, photonic-based quantum computers have emerged as a leading\u0000frontier. This article provides a comprehensive overview of advancements in\u0000photonic quantum computing, developed by leading industry players, examining\u0000current performance, architectural designs, and strategies for developing\u0000large-scale, fault-tolerant photonic quantum computers. It also highlights\u0000recent groundbreaking experiments that leverage the unique advantages of\u0000photonic technologies, underscoring their transformative potential. This review\u0000captures a pivotal moment of photonic quantum computing in the noisy\u0000intermediate-scale quantum (NISQ) era, offering insights into how photonic\u0000quantum computers might reshape the future of quantum computing.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202218","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}
Controlling the flow of photons is crucial for advancing quantum technologies. We introduce the concept of spatiotemporal photon blockade for nonreciprocal quantum absorption, utilizing space-time-periodic metasurfaces. Our study presents a methodology for experimentally realizing this effect, where photon frequency coherence with the metasurface's space-time modulation enables one-way quantum absorption. In this system, forward-traveling photons are energetically modulated and absorbed within the slab, while backward-traveling photons are transmitted without interaction. Our analysis includes band structure, isofrequency diagrams, and nonreciprocal absorption results. These findings lay the groundwork for developing nonreciprocal quantum devices and enhancing photon management in milli-Kelvin temperature quantum systems.
{"title":"Spatiotemporal Photon Blockade for Nonreciprocal Quantum Absorption","authors":"Sajjad Taravati","doi":"arxiv-2409.08137","DOIUrl":"https://doi.org/arxiv-2409.08137","url":null,"abstract":"Controlling the flow of photons is crucial for advancing quantum\u0000technologies. We introduce the concept of spatiotemporal photon blockade for\u0000nonreciprocal quantum absorption, utilizing space-time-periodic metasurfaces.\u0000Our study presents a methodology for experimentally realizing this effect,\u0000where photon frequency coherence with the metasurface's space-time modulation\u0000enables one-way quantum absorption. In this system, forward-traveling photons\u0000are energetically modulated and absorbed within the slab, while\u0000backward-traveling photons are transmitted without interaction. Our analysis\u0000includes band structure, isofrequency diagrams, and nonreciprocal absorption\u0000results. These findings lay the groundwork for developing nonreciprocal quantum\u0000devices and enhancing photon management in milli-Kelvin temperature quantum\u0000systems.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202225","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}
Samuel E. Fontaine, Colin Vendromin, Trevor J. Steiner, Amirali Atrli, Lillian Thiel, Joshua Castro, Galan Moody, John Bowers, Marco Liscidini, J. E. Sipe
We explore how III-V semiconductor microring resonators can efficiently generate photon pairs and squeezed vacuum states via spontaneous parametric down-conversion by utilizing their built-in quasi phase matching and modal dispersion. We present an analytic expression for the biphoton wave function of photon pairs generated by weak pump pulses, and characterize the squeezed states that result under stronger pumping conditions. Our model includes loss, and captures the statistics of the scattered photons. A detailed sample calculation shows that for low pump powers conversion efficiencies of 10$^{-5}$, corresponding to a rate of 39 MHz for a pump power of 1 $mu$W, are attainable for rudimentary structures such as a simple microring coupled to a waveguide, in both the continuous wave and pulsed excitation regimes. Our results suggest that high levels of squeezing and pump depletion are attainable, possibly leading to the deterministic generation of non-Gaussian states
{"title":"Photon pair generation via down-conversion in III-V semiconductor microrings: modal dispersion and quasi-phase matching","authors":"Samuel E. Fontaine, Colin Vendromin, Trevor J. Steiner, Amirali Atrli, Lillian Thiel, Joshua Castro, Galan Moody, John Bowers, Marco Liscidini, J. E. Sipe","doi":"arxiv-2409.08230","DOIUrl":"https://doi.org/arxiv-2409.08230","url":null,"abstract":"We explore how III-V semiconductor microring resonators can efficiently\u0000generate photon pairs and squeezed vacuum states via spontaneous parametric\u0000down-conversion by utilizing their built-in quasi phase matching and modal\u0000dispersion. We present an analytic expression for the biphoton wave function of\u0000photon pairs generated by weak pump pulses, and characterize the squeezed\u0000states that result under stronger pumping conditions. Our model includes loss,\u0000and captures the statistics of the scattered photons. A detailed sample\u0000calculation shows that for low pump powers conversion efficiencies of\u000010$^{-5}$, corresponding to a rate of 39 MHz for a pump power of 1 $mu$W, are\u0000attainable for rudimentary structures such as a simple microring coupled to a\u0000waveguide, in both the continuous wave and pulsed excitation regimes. Our\u0000results suggest that high levels of squeezing and pump depletion are\u0000attainable, possibly leading to the deterministic generation of non-Gaussian\u0000states","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202217","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}
Ali Emami Kopaei, Karthik Subramaniam Eswaran, Arkadiusz Kosior, Daniel Hodgson, Andrey Matsko, Hossein Taheri, Almut Beige, Krzysztof Sacha
Periodic driving of systems of particles can create crystalline structures in time. Such systems can be used to study solid-state physics phenomena in the time domain. In addition, it is possible to engineer the wave-number band structure of optical systems and to realize photonic time crystals by periodic temporal modulation of the material properties of the electromagnetic wave propagation medium. We introduce here a versatile averaged-permittivity approach which empowers emulating various condensed matter phases in the time dimension in a traveling wave resonator. This is achieved by utilizing temporal modulation of permittivity within a small segment of the resonator and the spatial shape of the segment. The required frequency and depth of the modulation are experimentally achievable, opening a pathway for research into the practical realisation of crystalline structures in time utilising microwave and optical systems.
{"title":"Towards Timetronics with Photonic Systems","authors":"Ali Emami Kopaei, Karthik Subramaniam Eswaran, Arkadiusz Kosior, Daniel Hodgson, Andrey Matsko, Hossein Taheri, Almut Beige, Krzysztof Sacha","doi":"arxiv-2409.07885","DOIUrl":"https://doi.org/arxiv-2409.07885","url":null,"abstract":"Periodic driving of systems of particles can create crystalline structures in\u0000time. Such systems can be used to study solid-state physics phenomena in the\u0000time domain. In addition, it is possible to engineer the wave-number band\u0000structure of optical systems and to realize photonic time crystals by periodic\u0000temporal modulation of the material properties of the electromagnetic wave\u0000propagation medium. We introduce here a versatile averaged-permittivity\u0000approach which empowers emulating various condensed matter phases in the time\u0000dimension in a traveling wave resonator. This is achieved by utilizing temporal\u0000modulation of permittivity within a small segment of the resonator and the\u0000spatial shape of the segment. The required frequency and depth of the\u0000modulation are experimentally achievable, opening a pathway for research into\u0000the practical realisation of crystalline structures in time utilising microwave\u0000and optical systems.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202284","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}
V. A. Zaytsev, V. A. Yerokhin, C. H. Keitel, N. S. Oreshkina
Self-energy and vacuum polarization effects in quantum electrodynamics (QED) are calculated for the supercritical Coulomb field, where Dirac energy levels become embedded in the negative-energy continuum. In this regime, the quantum vacuum becomes unstable, resulting in spontaneous electron-positron pair creation. By calculating the imaginary part of the QED correction, we gain access to an unexplored channel of vacuum instability: radiative spontaneous pair creation. Our results show that this radiative channel is greatly enhanced in the vicinity of the threshold of the supercritical regime, providing evidence for nonperturbative effects with respect to the fine-structure constant $alpha$. We therefore conjecture that the total probability of spontaneous pair creation could differ significantly from the predictions of Dirac theory, especially near the supercritical threshold.
针对超临界库仑场计算了量子电动力学（QED）中的自能效应和真空极化效应，在超临界库仑场中，狄拉克能级嵌入负能连续体中。在这种情况下，量子真空变得不稳定，导致自发的电子-正电子对产生。通过计算 QED 修正的虚部，我们获得了一个尚未探索的真空不稳定通道：辐射自发电子对产生。我们的结果表明，这一辐射通道在超临界阈值附近被大大增强，为精细结构常数$alpha$的非扰动效应提供了证据。因此，我们推测自发成对的总概率可能与狄拉克理论的预测有很大不同，尤其是在超临界阈值附近。
{"title":"QED Corrections in Unstable Vacuum","authors":"V. A. Zaytsev, V. A. Yerokhin, C. H. Keitel, N. S. Oreshkina","doi":"arxiv-2409.08121","DOIUrl":"https://doi.org/arxiv-2409.08121","url":null,"abstract":"Self-energy and vacuum polarization effects in quantum electrodynamics (QED)\u0000are calculated for the supercritical Coulomb field, where Dirac energy levels\u0000become embedded in the negative-energy continuum. In this regime, the quantum\u0000vacuum becomes unstable, resulting in spontaneous electron-positron pair\u0000creation. By calculating the imaginary part of the QED correction, we gain\u0000access to an unexplored channel of vacuum instability: radiative spontaneous\u0000pair creation. Our results show that this radiative channel is greatly enhanced\u0000in the vicinity of the threshold of the supercritical regime, providing\u0000evidence for nonperturbative effects with respect to the fine-structure\u0000constant $alpha$. We therefore conjecture that the total probability of\u0000spontaneous pair creation could differ significantly from the predictions of\u0000Dirac theory, especially near the supercritical threshold.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202293","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}
Mohsen Bagherimehrab, Dominic W. Berry, Philipp Schleich, Abdulrahman Aldossary, Jorge A. Campos Gonzalez Angulo, Alan Aspuru-Guzik
Hamiltonian simulation using product formulas is arguably the most straightforward and practical approach for algorithmic simulation of a quantum system's dynamics on a quantum computer. Here we present corrected product formulas (CPFs), a variation of product formulas achieved by injecting auxiliary terms called correctors into standard product formulas. We establish several correctors that greatly improve the accuracy of standard product formulas for simulating Hamiltonians comprised of two partitions that can be exactly simulated, a common feature of lattice Hamiltonians, while only adding a small additive or multiplicative factor to the simulation cost. We show that correctors are particularly advantageous for perturbed systems, where one partition has a relatively small norm compared to the other, as they allow the small norm to be utilized as an additional parameter for controlling the simulation error. We demonstrate the performance of CPFs by numerical simulations for several lattice Hamiltonians. Numerical results show our theoretical error bound for CPFs matches or exceeds the empirical error of standard product formulas for these systems. CPFs could be a valuable algorithmic tool for early fault-tolerant quantum computers with limited computing resources. As for standard product formulas, CPFs could also be used for simulations on a classical computer.
{"title":"Faster Algorithmic Quantum and Classical Simulations by Corrected Product Formulas","authors":"Mohsen Bagherimehrab, Dominic W. Berry, Philipp Schleich, Abdulrahman Aldossary, Jorge A. Campos Gonzalez Angulo, Alan Aspuru-Guzik","doi":"arxiv-2409.08265","DOIUrl":"https://doi.org/arxiv-2409.08265","url":null,"abstract":"Hamiltonian simulation using product formulas is arguably the most\u0000straightforward and practical approach for algorithmic simulation of a quantum\u0000system's dynamics on a quantum computer. Here we present corrected product\u0000formulas (CPFs), a variation of product formulas achieved by injecting\u0000auxiliary terms called correctors into standard product formulas. We establish\u0000several correctors that greatly improve the accuracy of standard product\u0000formulas for simulating Hamiltonians comprised of two partitions that can be\u0000exactly simulated, a common feature of lattice Hamiltonians, while only adding\u0000a small additive or multiplicative factor to the simulation cost. We show that\u0000correctors are particularly advantageous for perturbed systems, where one\u0000partition has a relatively small norm compared to the other, as they allow the\u0000small norm to be utilized as an additional parameter for controlling the\u0000simulation error. We demonstrate the performance of CPFs by numerical\u0000simulations for several lattice Hamiltonians. Numerical results show our\u0000theoretical error bound for CPFs matches or exceeds the empirical error of\u0000standard product formulas for these systems. CPFs could be a valuable\u0000algorithmic tool for early fault-tolerant quantum computers with limited\u0000computing resources. As for standard product formulas, CPFs could also be used\u0000for simulations on a classical computer.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202220","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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