Boris Bourdoncle, Pierre-Emmanuel Emeriau, Paul Hilaire, Shane Mansfield, Luka Music, Stephen Wein
Secure Delegated Quantum Computation (SDQC) protocols are a vital piece of the future quantum information processing global architecture since they allow end-users to perform their valuable computations on remote quantum servers without fear that a malicious quantum service provider or an eavesdropper might acquire some information about their data or algorithm. They also allow end-users to check that their computation has been performed as they have specified it. However, existing protocols all have drawbacks that limit their usage in the real world. Most require the client to either operate a single-qubit source or perform single-qubit measurements, thus requiring them to still have some quantum technological capabilities albeit restricted, or require the server to perform operations which are hard to implement on real hardware (e.g isolate single photons from laser pulses and polarisation-preserving photon-number quantum non-demolition measurements). Others remove the need for quantum communications entirely but this comes at a cost in terms of security guarantees and memory overhead on the server's side. We present an SDQC protocol which drastically reduces the technological requirements of both the client and the server while providing information-theoretic composable security. More precisely, the client only manipulates an attenuated laser pulse, while the server only handles interacting quantum emitters with a structure capable of generating spin-photon entanglement. The quantum emitter acts as both a converter from coherent laser pulses to polarisation-encoded qubits and an entanglement generator. Such devices have recently been used to demonstrate the largest entangled photonic state to date, thus hinting at the readiness of our protocol for experimental implementations.
{"title":"Towards practical secure delegated quantum computing with semi-classical light","authors":"Boris Bourdoncle, Pierre-Emmanuel Emeriau, Paul Hilaire, Shane Mansfield, Luka Music, Stephen Wein","doi":"arxiv-2409.12103","DOIUrl":"https://doi.org/arxiv-2409.12103","url":null,"abstract":"Secure Delegated Quantum Computation (SDQC) protocols are a vital piece of\u0000the future quantum information processing global architecture since they allow\u0000end-users to perform their valuable computations on remote quantum servers\u0000without fear that a malicious quantum service provider or an eavesdropper might\u0000acquire some information about their data or algorithm. They also allow\u0000end-users to check that their computation has been performed as they have\u0000specified it. However, existing protocols all have drawbacks that limit their usage in the\u0000real world. Most require the client to either operate a single-qubit source or\u0000perform single-qubit measurements, thus requiring them to still have some\u0000quantum technological capabilities albeit restricted, or require the server to\u0000perform operations which are hard to implement on real hardware (e.g isolate\u0000single photons from laser pulses and polarisation-preserving photon-number\u0000quantum non-demolition measurements). Others remove the need for quantum\u0000communications entirely but this comes at a cost in terms of security\u0000guarantees and memory overhead on the server's side. We present an SDQC protocol which drastically reduces the technological\u0000requirements of both the client and the server while providing\u0000information-theoretic composable security. More precisely, the client only\u0000manipulates an attenuated laser pulse, while the server only handles\u0000interacting quantum emitters with a structure capable of generating spin-photon\u0000entanglement. The quantum emitter acts as both a converter from coherent laser\u0000pulses to polarisation-encoded qubits and an entanglement generator. Such\u0000devices have recently been used to demonstrate the largest entangled photonic\u0000state to date, thus hinting at the readiness of our protocol for experimental\u0000implementations.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248074","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}
Ivan Iakoupov, Victor M. Bastidas, Yuichiro Matsuzaki, Shiro Saito, William J. Munro
Spin amplification is the process that ideally increases the number of excited spins if there was one excited spin to begin with. Using optimal control techniques to find classical drive pulse shapes, we show that spin amplification can be done in the previously unexplored regime with amplification times comparable to the timescale set by the interaction terms in the Hamiltonian. This is an order of magnitude faster than the previous protocols and makes spin amplification possible even with significant decoherence and inhomogeneity in the spin system. The initial spin excitation can be delocalized over the entire ensemble, which is a more typical situation when a photon is collectively absorbed by the spins. We focus on the superconducting persistent-current artificial atoms as spins, but this approach can be applied to other kinds of strongly-interacting spins, including the Rydberg atoms.
{"title":"Spin amplification in realistic systems","authors":"Ivan Iakoupov, Victor M. Bastidas, Yuichiro Matsuzaki, Shiro Saito, William J. Munro","doi":"arxiv-2409.11956","DOIUrl":"https://doi.org/arxiv-2409.11956","url":null,"abstract":"Spin amplification is the process that ideally increases the number of\u0000excited spins if there was one excited spin to begin with. Using optimal\u0000control techniques to find classical drive pulse shapes, we show that spin\u0000amplification can be done in the previously unexplored regime with\u0000amplification times comparable to the timescale set by the interaction terms in\u0000the Hamiltonian. This is an order of magnitude faster than the previous\u0000protocols and makes spin amplification possible even with significant\u0000decoherence and inhomogeneity in the spin system. The initial spin excitation\u0000can be delocalized over the entire ensemble, which is a more typical situation\u0000when a photon is collectively absorbed by the spins. We focus on the\u0000superconducting persistent-current artificial atoms as spins, but this approach\u0000can be applied to other kinds of strongly-interacting spins, including the\u0000Rydberg atoms.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268300","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 state estimation is a fundamental task in quantum information theory, where one estimates real parameters continuously embedded in a family of quantum states. In the theory of quantum state estimation, the widely used Cram'er Rao approach which considers local estimation gives the ultimate precision bound of quantum state estimation in terms of the quantum Fisher information. However practical scenarios need not offer much prior information about the parameters to be estimated, and the local estimation setting need not apply. In general, it is unclear whether the Cram'er-Rao approach is applicable for global estimation instead of local estimation. In this paper, we find situations where the Cram'er-Rao approach does and does not work for quantum state estimation problems involving a family of bosonic states in a non-IID setting, where we only use one copy of the bosonic quantum state in the large number of bosons setting. Our result highlights the importance of caution when using the results of the Cram'er-Rao approach to extrapolate to the global estimation setting.
{"title":"The Cramér-Rao approach and global quantum estimation of bosonic states","authors":"Masahito Hayashi, Yingkai Ouyang","doi":"arxiv-2409.11842","DOIUrl":"https://doi.org/arxiv-2409.11842","url":null,"abstract":"Quantum state estimation is a fundamental task in quantum information theory,\u0000where one estimates real parameters continuously embedded in a family of\u0000quantum states. In the theory of quantum state estimation, the widely used\u0000Cram'er Rao approach which considers local estimation gives the ultimate\u0000precision bound of quantum state estimation in terms of the quantum Fisher\u0000information. However practical scenarios need not offer much prior information\u0000about the parameters to be estimated, and the local estimation setting need not\u0000apply. In general, it is unclear whether the Cram'er-Rao approach is\u0000applicable for global estimation instead of local estimation. In this paper, we\u0000find situations where the Cram'er-Rao approach does and does not work for\u0000quantum state estimation problems involving a family of bosonic states in a\u0000non-IID setting, where we only use one copy of the bosonic quantum state in the\u0000large number of bosons setting. Our result highlights the importance of caution\u0000when using the results of the Cram'er-Rao approach to extrapolate to the\u0000global estimation setting.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248110","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}
Variational Quantum Imaginary Time Evolution (VQITE) is a leading technique for ground state preparation on quantum computers. A significant computational challenge of VQITE is the determination of the quantum geometric tensor. We show that requiring the imaginary-time evolution to be correct only when projected onto a chosen set of operators allows to achieve a twofold reduction in circuit depth by bypassing fidelity estimations, and reduces measurement complexity from quadratic to linear in the number of parameters. We demonstrate by a simulation of the transverse-field Ising model that our algorithm achieves a several orders of magnitude improvement in the number of measurements required for the same accuracy.
{"title":"Operator-Projected Variational Quantum Imaginary Time Evolution","authors":"Aeishah Ameera Anuar, Francois Jamet, Fabio Gironella, Fedor Simkovic IV, Riccardo Rossi","doi":"arxiv-2409.12018","DOIUrl":"https://doi.org/arxiv-2409.12018","url":null,"abstract":"Variational Quantum Imaginary Time Evolution (VQITE) is a leading technique\u0000for ground state preparation on quantum computers. A significant computational\u0000challenge of VQITE is the determination of the quantum geometric tensor. We\u0000show that requiring the imaginary-time evolution to be correct only when\u0000projected onto a chosen set of operators allows to achieve a twofold reduction\u0000in circuit depth by bypassing fidelity estimations, and reduces measurement\u0000complexity from quadratic to linear in the number of parameters. We demonstrate\u0000by a simulation of the transverse-field Ising model that our algorithm achieves\u0000a several orders of magnitude improvement in the number of measurements\u0000required for the same accuracy.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268299","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 celebrated Bell's no-go theorem rules out the hidden-variable theories falling in the hypothesis of locality and causality, by requiring the theory to model the quantum correlation-at-a-distance phenomena. Here I develop an independent no-go theorem, by inspecting the ability of a theory to model quantum emph{circuits}. If a theory is compatible with quantum mechanics, then the problems of solving its mathematical models must be as hard as calculating the output of quantum circuits, i.e., as hard as quantum computing. Rigorously, I provide complexity classes capturing the idea of sampling from sequential (causal) theories and from post-selection-based (retro-causal) theories; I show that these classes fail to cover the computational complexity of sampling from quantum circuits. The result is based on widely accepted conjectures on the superiority of quantum computers over classical ones. The result represents a no-go theorem that rules out a large family of sequential and post-selection-based theories. I discuss the hypothesis of the no-go theorem and the possible ways to circumvent them. In particular, I discuss the Schulman model and its extensions, which is retro-causal and is able to model quantum correlation-at-a-distance phenomena: I provides clues suggesting that it escapes the hypothesis of the no-go theorem.
{"title":"A no-go theorem for sequential and retro-causal hidden-variable theories based on computational complexity","authors":"Doriano Brogioli","doi":"arxiv-2409.11792","DOIUrl":"https://doi.org/arxiv-2409.11792","url":null,"abstract":"The celebrated Bell's no-go theorem rules out the hidden-variable theories\u0000falling in the hypothesis of locality and causality, by requiring the theory to\u0000model the quantum correlation-at-a-distance phenomena. Here I develop an\u0000independent no-go theorem, by inspecting the ability of a theory to model\u0000quantum emph{circuits}. If a theory is compatible with quantum mechanics, then\u0000the problems of solving its mathematical models must be as hard as calculating\u0000the output of quantum circuits, i.e., as hard as quantum computing. Rigorously,\u0000I provide complexity classes capturing the idea of sampling from sequential\u0000(causal) theories and from post-selection-based (retro-causal) theories; I show\u0000that these classes fail to cover the computational complexity of sampling from\u0000quantum circuits. The result is based on widely accepted conjectures on the\u0000superiority of quantum computers over classical ones. The result represents a\u0000no-go theorem that rules out a large family of sequential and\u0000post-selection-based theories. I discuss the hypothesis of the no-go theorem\u0000and the possible ways to circumvent them. In particular, I discuss the Schulman\u0000model and its extensions, which is retro-causal and is able to model quantum\u0000correlation-at-a-distance phenomena: I provides clues suggesting that it\u0000escapes the hypothesis of the no-go theorem.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248077","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 spin Hall insulators with a pair of helical edge states and proximity-induced superconductivity have been shown to support second-order topological superconductors with Majorana corner modes. As the Majorana corner modes are originated from the helical edge states of the quantum spin Hall insulators, whether quantum spin Hall insulators with multiple pairs of helical edge states and proximity-induced superconductivity can give rise to second-order topological superconductors with multifold Majorana corner modes is an interesting question to address. In this work, we consider a quantum spin Hall insulator with two pairs of helical edge states. We find robust twofold Majorana corner modes can be achieved when the helical edge states are gapped by a combined action of a magnetic exchange field and an $s$-wave pairing, or an $s+p$ mixed-parity pairing. The stability of two Majorana zero modes per corner under the action of magnetic exchange fields is attributed to the protection from the chiral symmetry. Our study reveals that heterostructures composed of superconductors and quantum spin Hall insulators with multiple pairs of helical edge states could serve as a platform to pursue multifold Majorana corner modes.
{"title":"Multifold Majorana corner modes arising from multiple pairs of helical edge states","authors":"Zhiwei Yin, Haoshu Li, Zhongbo Yan, Shaolong Wan","doi":"arxiv-2409.11791","DOIUrl":"https://doi.org/arxiv-2409.11791","url":null,"abstract":"Quantum spin Hall insulators with a pair of helical edge states and\u0000proximity-induced superconductivity have been shown to support second-order\u0000topological superconductors with Majorana corner modes. As the Majorana corner\u0000modes are originated from the helical edge states of the quantum spin Hall\u0000insulators, whether quantum spin Hall insulators with multiple pairs of helical\u0000edge states and proximity-induced superconductivity can give rise to\u0000second-order topological superconductors with multifold Majorana corner modes\u0000is an interesting question to address. In this work, we consider a quantum spin\u0000Hall insulator with two pairs of helical edge states. We find robust twofold\u0000Majorana corner modes can be achieved when the helical edge states are gapped\u0000by a combined action of a magnetic exchange field and an $s$-wave pairing, or\u0000an $s+p$ mixed-parity pairing. The stability of two Majorana zero modes per\u0000corner under the action of magnetic exchange fields is attributed to the\u0000protection from the chiral symmetry. Our study reveals that heterostructures\u0000composed of superconductors and quantum spin Hall insulators with multiple\u0000pairs of helical edge states could serve as a platform to pursue multifold\u0000Majorana corner modes.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248115","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 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":"arxiv-2409.12174","DOIUrl":"https://doi.org/arxiv-2409.12174","url":null,"abstract":"We compare the performance of protective quantum measurements to that of\u0000standard projective measurements. Performance is quantified in terms of the\u0000uncertainty in the measured expectation value. We derive an expression for the\u0000relative performance of these two types of quantum measurements and show\u0000explicitly that protective measurements can provide a significant performance\u0000advantage over standard projective measurements.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248072","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 report the design and theoretical analysis of Wannier-Stark ladders of diamond Lamb wave resonators (LWRs) that can feature compression modes with ultralow damping rates and host spin qubits with excellent optical and spin properties. Three nearest-neighbor coupling schemes with distinct geometric configurations and a large range of coupling rates have been explored for the realization of Wannier-Stark ladders of LWRs, potentially enabling long-range connectivity between spin qubits through their interactions with mechanical vibrations. Additional analysis on the effects of disorder indicates that the proposed Wannier-Stark ladder can be robust against realistic experimental imperfections. The development of mechanical quantum networks of spin qubits with long-range connectivity can open the door to the implementation of newly developed quantum low-density parity-check codes in solid-state systems.
{"title":"Mechanical Wannier-Stark Ladder of Diamond Spin-Mechanical Lamb Wave Resonators","authors":"Philip Andrango, Hailin Wang","doi":"arxiv-2409.12149","DOIUrl":"https://doi.org/arxiv-2409.12149","url":null,"abstract":"We report the design and theoretical analysis of Wannier-Stark ladders of\u0000diamond Lamb wave resonators (LWRs) that can feature compression modes with\u0000ultralow damping rates and host spin qubits with excellent optical and spin\u0000properties. Three nearest-neighbor coupling schemes with distinct geometric\u0000configurations and a large range of coupling rates have been explored for the\u0000realization of Wannier-Stark ladders of LWRs, potentially enabling long-range\u0000connectivity between spin qubits through their interactions with mechanical\u0000vibrations. Additional analysis on the effects of disorder indicates that the\u0000proposed Wannier-Stark ladder can be robust against realistic experimental\u0000imperfections. The development of mechanical quantum networks of spin qubits\u0000with long-range connectivity can open the door to the implementation of newly\u0000developed quantum low-density parity-check codes in solid-state systems.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248073","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}
Among all the physical platforms for the realization of a Quantum Processing Unit (QPU), neutral atom devices are emerging as one of the main players. Their scalability, long coherence times, and the absence of manufacturing errors make them a viable candidate.. Here, we use a binary classifier model whose training is reformulated as a Quadratic Unconstrained Binary Optimization (QUBO) problem and implemented on a neutral atom QPU. In particular, we test it on a Credit Card Fraud (CCF) dataset. We propose several versions of the model, including exploiting the model in ensemble learning schemes. We show that one of our proposed versions seems to achieve higher performance and lower errors, validating our claims by comparing the most popular Machine Learning (ML) models with QUBO SVM models trained with ideal, noisy simulations and even via a real QPU. In addition, the data obtained via real QPU extend up to 24 atoms, confirming the model's noise robustness. We also show, by means of numerical simulations, how a certain amount of noise leads surprisingly to enhanced results. Our results represent a further step towards new quantum ML algorithms running on neutral atom QPUs for cybersecurity applications.
{"title":"QUBO-based SVM for credit card fraud detection on a real QPU","authors":"Ettore Canonici, Filippo Caruso","doi":"arxiv-2409.11876","DOIUrl":"https://doi.org/arxiv-2409.11876","url":null,"abstract":"Among all the physical platforms for the realization of a Quantum Processing\u0000Unit (QPU), neutral atom devices are emerging as one of the main players. Their\u0000scalability, long coherence times, and the absence of manufacturing errors make\u0000them a viable candidate.. Here, we use a binary classifier model whose training\u0000is reformulated as a Quadratic Unconstrained Binary Optimization (QUBO) problem\u0000and implemented on a neutral atom QPU. In particular, we test it on a Credit\u0000Card Fraud (CCF) dataset. We propose several versions of the model, including\u0000exploiting the model in ensemble learning schemes. We show that one of our\u0000proposed versions seems to achieve higher performance and lower errors,\u0000validating our claims by comparing the most popular Machine Learning (ML)\u0000models with QUBO SVM models trained with ideal, noisy simulations and even via\u0000a real QPU. In addition, the data obtained via real QPU extend up to 24 atoms,\u0000confirming the model's noise robustness. We also show, by means of numerical\u0000simulations, how a certain amount of noise leads surprisingly to enhanced\u0000results. Our results represent a further step towards new quantum ML algorithms\u0000running on neutral atom QPUs for cybersecurity applications.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248076","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}
Wilson S. Martins, Federico Carollo, Kay Brandner, Igor Lesanovsky
Open systems that are weakly coupled to a thermal environment and driven by fast, periodically oscillating fields are commonly assumed to approach an equilibrium-like steady state with respect to a truncated Floquet-Magnus Hamiltonian. Using a general argument based on Fermi's golden rule, we show that such Floquet-Gibbs states emerge naturally in periodically modulated Rydberg atomic systems, whose lab-frame Hamiltonian is a quasiperiodic function of time. Our approach applies as long as the inherent Bohr frequencies of the system, the modulation frequency and the frequency of the driving laser, which is necessary to uphold high-lying Rydberg excitations, are well separated. To corroborate our analytical results, we analyze a realistic model of up to five interacting Rydberg atoms with periodically changing detuning. We demonstrate numerically that the second-order Floquet-Gibbs state of this system is essentially indistinguishable from the steady state of the corresponding Redfield equation if the modulation and driving frequencies are sufficiently large.
{"title":"Quasiperiodic Floquet-Gibbs states in Rydberg atomic systems","authors":"Wilson S. Martins, Federico Carollo, Kay Brandner, Igor Lesanovsky","doi":"arxiv-2409.12044","DOIUrl":"https://doi.org/arxiv-2409.12044","url":null,"abstract":"Open systems that are weakly coupled to a thermal environment and driven by\u0000fast, periodically oscillating fields are commonly assumed to approach an\u0000equilibrium-like steady state with respect to a truncated Floquet-Magnus\u0000Hamiltonian. Using a general argument based on Fermi's golden rule, we show\u0000that such Floquet-Gibbs states emerge naturally in periodically modulated\u0000Rydberg atomic systems, whose lab-frame Hamiltonian is a quasiperiodic function\u0000of time. Our approach applies as long as the inherent Bohr frequencies of the\u0000system, the modulation frequency and the frequency of the driving laser, which\u0000is necessary to uphold high-lying Rydberg excitations, are well separated. To\u0000corroborate our analytical results, we analyze a realistic model of up to five\u0000interacting Rydberg atoms with periodically changing detuning. We demonstrate\u0000numerically that the second-order Floquet-Gibbs state of this system is\u0000essentially indistinguishable from the steady state of the corresponding\u0000Redfield equation if the modulation and driving frequencies are sufficiently\u0000large.","PeriodicalId":501226,"journal":{"name":"arXiv - PHYS - Quantum Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248108","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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