Foster Thompson, Daniel K. J. Boneß, Mark Dykman, Alex Kamenev
Parametrically driven oscillators can emerge as a basis for the next generation of qubits. Classically, these systems exhibit two stable oscillatory states with opposite phases. Upon quantization, these states turn into a pair of closely spaced Floquet states, which can serve as the logical basis for a qubit. However, interaction with the environment induces phase-slip events which set a limit on qubit coherence. Such phase slips persist even at zero temperature due to a mechanism known as quantum activation cite{QuantumActivation}. In contrast to conventional tunneling, the quantum activation is described by a {em real-time} instanton trajectory in the complexified phase space of the system. In this work, we show that the phase-slip rate is exponentially sensitive to weak AC perturbations. The spectrum of the system's response -- captured by the so-called logarithmic susceptibility (LS) -- enables a direct observation of characteristic features of real-time instantons. Studying this spectrum suggests new means of efficient qubit control.
{"title":"Spectroscopy of quantum phase slips: Visualizing complex real-time instantons","authors":"Foster Thompson, Daniel K. J. Boneß, Mark Dykman, Alex Kamenev","doi":"10.1103/bkyx-wwv1","DOIUrl":"https://doi.org/10.1103/bkyx-wwv1","url":null,"abstract":"Parametrically driven oscillators can emerge as a basis for the next generation of qubits. Classically, these systems exhibit two stable oscillatory states with opposite phases. Upon quantization, these states turn into a pair of closely spaced Floquet states, which can serve as the logical basis for a qubit. However, interaction with the environment induces phase-slip events which set a limit on qubit coherence. Such phase slips persist even at zero temperature due to a mechanism known as quantum activation cite{QuantumActivation}. In contrast to conventional tunneling, the quantum activation is described by a {em real-time} instanton trajectory in the complexified phase space of the system. In this work, we show that the phase-slip rate is exponentially sensitive to weak AC perturbations. The spectrum of the system's response -- captured by the so-called logarithmic susceptibility (LS) -- enables a direct observation of characteristic features of real-time instantons. Studying this spectrum suggests new means of efficient qubit control.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"113 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://arxiv.org/pdf/2512.24495","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147895218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lina Bielke, Samuel Schöpa, Falk-Erik Wiechmann, Franziska Fennel, D. Bauer
The generation of high harmonics is a strongly nonlinear effect that allows to probe properties of the target and to study electron dynamics in matter. It has been investigated in many different kinds of targets, including molecular gases, liquids and solids. Recently, high-harmonic generation was studied in organic molecular crystals by Wiechmann et al. [Nat. Commun. 16, 9890 (2025)]. It was found that the laser-polarization-dependent harmonic yield is sensitive to the weak couplings between nearest- and next-nearest-neighbor molecules. In this paper, the impact of the laser polarization angle and the intermolecular interaction on the harmonic yield is examined in detail using a simple but insightful two-dimensional tight-binding system that models a molecular dimer, i.e. two weakly coupled molecules. We find that the intensities of lower harmonic orders tend to maximize for a laser polarization direction aligning with the molecular axes, whereas higher harmonic orders rather show the strongest yield for a polarization direction along the intermolecular axis. We further demonstrate that the harmonic order at which the maximum flips from the molecular to the intermolecular direction strongly depends on the intermolecular coupling strength. To gain a deeper insight into the origins of the findings, we include a detailed adiabatic analysis, showing that the flipping of the maximum yield towards the intermolecular direction is already contained qualitatively in the adiabatically following states.
高次谐波的产生是一种强烈的非线性效应，它允许探测目标的性质和研究物质中的电子动力学。它已经在许多不同类型的目标中进行了研究，包括分子气体、液体和固体。最近，Wiechmann等人研究了有机分子晶体中的高谐波产生[Nat. comm . 16,9890(2025)]。研究发现，激光偏振相关的谐波产率对最近邻分子和次近邻分子之间的弱耦合非常敏感。在本文中，激光偏振角和分子间相互作用对谐波产率的影响使用一个简单但深刻的二维紧密结合系统进行了详细的研究，该系统模拟了一个分子二聚体，即两个弱耦合分子。我们发现，当激光偏振方向与分子轴对齐时，低次谐波的强度趋于最大化，而高次谐波的强度在沿分子间轴的偏振方向上表现出最强的产率。我们进一步证明了从分子方向到分子间方向的最大翻转的谐波顺序强烈依赖于分子间耦合强度。为了更深入地了解这些发现的起源，我们包括了一个详细的绝热分析，表明最大产率向分子间方向的翻转已经定性地包含在绝热以下状态中。
{"title":"High-harmonic generation from two weakly coupled molecules: A simple tight-binding model","authors":"Lina Bielke, Samuel Schöpa, Falk-Erik Wiechmann, Franziska Fennel, D. Bauer","doi":"10.1103/7ljs-sbpy","DOIUrl":"https://doi.org/10.1103/7ljs-sbpy","url":null,"abstract":"The generation of high harmonics is a strongly nonlinear effect that allows to probe properties of the target and to study electron dynamics in matter. It has been investigated in many different kinds of targets, including molecular gases, liquids and solids. Recently, high-harmonic generation was studied in organic molecular crystals by Wiechmann et al. [Nat. Commun. 16, 9890 (2025)]. It was found that the laser-polarization-dependent harmonic yield is sensitive to the weak couplings between nearest- and next-nearest-neighbor molecules. In this paper, the impact of the laser polarization angle and the intermolecular interaction on the harmonic yield is examined in detail using a simple but insightful two-dimensional tight-binding system that models a molecular dimer, i.e. two weakly coupled molecules. We find that the intensities of lower harmonic orders tend to maximize for a laser polarization direction aligning with the molecular axes, whereas higher harmonic orders rather show the strongest yield for a polarization direction along the intermolecular axis. We further demonstrate that the harmonic order at which the maximum flips from the molecular to the intermolecular direction strongly depends on the intermolecular coupling strength. To gain a deeper insight into the origins of the findings, we include a detailed adiabatic analysis, showing that the flipping of the maximum yield towards the intermolecular direction is already contained qualitatively in the adiabatically following states.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"113 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://arxiv.org/pdf/2512.02623","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147919405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anonymous, Philippe Lewalle, Yipei Zhang, K. Birgitta Whaley
{"title":"Noise-canceling quantum feedback: Non-Hermitian dynamics with applications to state preparation and magic state distillation","authors":"Anonymous, Philippe Lewalle, Yipei Zhang, K. Birgitta Whaley","doi":"10.1103/cnxj-m1wn","DOIUrl":"https://doi.org/10.1103/cnxj-m1wn","url":null,"abstract":"","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"113 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147901461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We address the control of the dynamics of both population and coherence phase in an open two-level quantum system employing a single external control field. The system dynamics is described by a Markovian master equation that takes into account dephasing and thermal noise. The control is engineered by inverting the underlying equations of motion, which yields an analytical expression for the control field in terms of user-specified time-dependent functions for the population and coherence phase. Our approach allows us to dictate not only the initial and final populations and phases, but the full dynamics of these quantities. The chosen functions for population and phase have to conform to certain constraints indicated in our analysis. Our methodology also reveals the possible transitions for given initial conditions and environmental noise parameters.
{"title":"Simultaneous control of populations and coherence phase of open two-level quantum systems with a single pulse","authors":"Gustavo Fernandes da Costa, Emanuel F. de Lima","doi":"10.1103/x2g9-wpk6","DOIUrl":"https://doi.org/10.1103/x2g9-wpk6","url":null,"abstract":"We address the control of the dynamics of both population and coherence phase in an open two-level quantum system employing a single external control field. The system dynamics is described by a Markovian master equation that takes into account dephasing and thermal noise. The control is engineered by inverting the underlying equations of motion, which yields an analytical expression for the control field in terms of user-specified time-dependent functions for the population and coherence phase. Our approach allows us to dictate not only the initial and final populations and phases, but the full dynamics of these quantities. The chosen functions for population and phase have to conform to certain constraints indicated in our analysis. Our methodology also reveals the possible transitions for given initial conditions and environmental noise parameters.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"112 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147907532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Exploring gravitational interactions between objects with small masses has become increasingly timely. Concurrently, oscillators with masses ranging between milligrams and grams in cavity optomechanical systems sparked interest for probing gravity and even investigating gravity-induced decoherence within massive mechanical systems. Here we present a measurement scheme for probing gravity in a microwave optomechanical setup that incorporates periodic gravitational modulation between the test mass and the driven source mass at the milligram scale. Optomechanically induced transparency (OMIT) can be utilized to sense the gravitational interactions between test masses and source masses. Specifically, the relative variation in the height of the OMIT peak, expressed as $|1+r{e}^{iensuremath{phi}}{|}^{2}ensuremath{-}1$, where $r$ represents the ratio of the amplitude of the gravitational driving force to the radiation pressure force of the probe tone and $ensuremath{phi}$ denotes their phase difference, can reach up to 2.3% under plausible experimental conditions. This work may facilitate cavity-optomechanical probing of gravitational coupling between milligram-scale mechanical oscillators, a mass regime where modifications to gravity, evidence for extra dimensions, or gravity-induced entanglement may emerge.
{"title":"Cavity-optomechanical probe of gravity between massive mechanical oscillators","authors":"Ziqian Tang, Wenlong Li, Huanying Sun, Xiaoxia Cai, Tiefu Li, Yulong Liu","doi":"10.1103/m2zy-3ywx","DOIUrl":"https://doi.org/10.1103/m2zy-3ywx","url":null,"abstract":"Exploring gravitational interactions between objects with small masses has become increasingly timely. Concurrently, oscillators with masses ranging between milligrams and grams in cavity optomechanical systems sparked interest for probing gravity and even investigating gravity-induced decoherence within massive mechanical systems. Here we present a measurement scheme for probing gravity in a microwave optomechanical setup that incorporates periodic gravitational modulation between the test mass and the driven source mass at the milligram scale. Optomechanically induced transparency (OMIT) can be utilized to sense the gravitational interactions between test masses and source masses. Specifically, the relative variation in the height of the OMIT peak, expressed as $|1+r{e}^{iensuremath{phi}}{|}^{2}ensuremath{-}1$, where $r$ represents the ratio of the amplitude of the gravitational driving force to the radiation pressure force of the probe tone and $ensuremath{phi}$ denotes their phase difference, can reach up to 2.3% under plausible experimental conditions. This work may facilitate cavity-optomechanical probing of gravitational coupling between milligram-scale mechanical oscillators, a mass regime where modifications to gravity, evidence for extra dimensions, or gravity-induced entanglement may emerge.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"112 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://arxiv.org/pdf/2506.13398","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147898654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In traditional research, chaos is frequently accompanied by nonlinearity, which typically stems from nonlinear interactions or external driving forces. However, in this paper, we present the chaotic behavior that is completely attributed to the nonlinear back-reaction of the non-Markovian environment. To be specific, we derive the dynamical equations of an optomechanical system and demonstrate that the nonlinearity (cause of chaos) in the equations arises entirely from the time-domain convolutions (TDCs) induced by non-Markovian corrections. Under Markovian conditions, these TDCs are reduced into constants, thereby losing the nonlinearity and ultimately leading to the disappearance of chaos. Furthermore, we also observe chaos generation in the absence of optomechanical couplings, which further confirms that the non-Markovian effect is the sole inducement of chaos and the environmental parameters play important roles in the generation of chaos. We hope these results may open a new direction to investigate chaotic dynamics purely caused by non-Markovian environments.
{"title":"Non-Markovian-environment-induced chaos in an optomechanical system","authors":"You-Lin Xiang, Xinyu Zhao, Yan Xia","doi":"10.1103/knfq-17nw","DOIUrl":"https://doi.org/10.1103/knfq-17nw","url":null,"abstract":"In traditional research, chaos is frequently accompanied by nonlinearity, which typically stems from nonlinear interactions or external driving forces. However, in this paper, we present the chaotic behavior that is completely attributed to the nonlinear back-reaction of the non-Markovian environment. To be specific, we derive the dynamical equations of an optomechanical system and demonstrate that the nonlinearity (cause of chaos) in the equations arises entirely from the time-domain convolutions (TDCs) induced by non-Markovian corrections. Under Markovian conditions, these TDCs are reduced into constants, thereby losing the nonlinearity and ultimately leading to the disappearance of chaos. Furthermore, we also observe chaos generation in the absence of optomechanical couplings, which further confirms that the non-Markovian effect is the sole inducement of chaos and the environmental parameters play important roles in the generation of chaos. We hope these results may open a new direction to investigate chaotic dynamics purely caused by non-Markovian environments.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"112 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://arxiv.org/pdf/2602.15402","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147890396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shengjun Sun, Z. Y. Li, Chunzhi Cui, Shuang Xu, H. Z. Shen
The non-Markovian effects of open quantum systems subjected to external environments are deemed to be valuable resources in quantum optics and quantum information processing. In this work, we construct the model Hamiltonian of three-level giant atom with multiple coupling points in the semi-infinite photonic waveguide via complex coupling coefficients and investigate the non-Markovian dynamics of the three-level giant atom driven by a classical laser field. In the non-Markovian regime, the traveling time of a photon between different coupling points is sufficiently large compared to the inverse of the bare relaxation rate of the giant atom. We derive the analytical expressions for the probability amplitudes of the driven three-level giant atom by solving a set of delay differential equations and obtain two independent conditions of bound states' formation that can inhibit the dissipation. We find two different types of bound states (including the static bound states and the periodic equal-amplitude oscillating bound states) and discuss the physical origins of the bound states' formation. Moreover, we discuss the case of the driven three-level giant atom interacting with the infinite photonic waveguide, where there is only one purely imaginary solution (i.e., only one bound-state condition exists) for its complex frequency (coming from the absence of mirror at one end of the waveguide) compared to that of a driven three-level giant atom coupling with a semi-infinite photonic waveguide. With this, we also find two different types of bound states, including the static bound state and the periodic equal-amplitude oscillating bound states. We study the influences of the phase in the coupling strength on the bound states in semi-infinite and infinite photonic waveguides. The presented protocol might open a way to better understand exactly the non-Markovian dynamics of driven multilevel giant atoms interacting with semi-infinite (or infinite) photonic waveguides.
{"title":"Non-Markovian dynamics of a driven three-level giant atom coupled to a semi-infinite waveguide via complex couplings","authors":"Shengjun Sun, Z. Y. Li, Chunzhi Cui, Shuang Xu, H. Z. Shen","doi":"10.1103/yqvq-4h1d","DOIUrl":"https://doi.org/10.1103/yqvq-4h1d","url":null,"abstract":"The non-Markovian effects of open quantum systems subjected to external environments are deemed to be valuable resources in quantum optics and quantum information processing. In this work, we construct the model Hamiltonian of three-level giant atom with multiple coupling points in the semi-infinite photonic waveguide via complex coupling coefficients and investigate the non-Markovian dynamics of the three-level giant atom driven by a classical laser field. In the non-Markovian regime, the traveling time of a photon between different coupling points is sufficiently large compared to the inverse of the bare relaxation rate of the giant atom. We derive the analytical expressions for the probability amplitudes of the driven three-level giant atom by solving a set of delay differential equations and obtain two independent conditions of bound states' formation that can inhibit the dissipation. We find two different types of bound states (including the static bound states and the periodic equal-amplitude oscillating bound states) and discuss the physical origins of the bound states' formation. Moreover, we discuss the case of the driven three-level giant atom interacting with the infinite photonic waveguide, where there is only one purely imaginary solution (i.e., only one bound-state condition exists) for its complex frequency (coming from the absence of mirror at one end of the waveguide) compared to that of a driven three-level giant atom coupling with a semi-infinite photonic waveguide. With this, we also find two different types of bound states, including the static bound state and the periodic equal-amplitude oscillating bound states. We study the influences of the phase in the coupling strength on the bound states in semi-infinite and infinite photonic waveguides. The presented protocol might open a way to better understand exactly the non-Markovian dynamics of driven multilevel giant atoms interacting with semi-infinite (or infinite) photonic waveguides.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"112 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147892488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
While two perfect phase-matching mechanisms exist in homogeneous single crystals, birefringent phase-matching (BPM) dominates for nonlinear optical applications. The anomalous-dispersion phase matching (ADPM), though demonstrated in gases and liquids, has not been established in crystals due to the parasitic material absorption that induces the anomalous dispersion in the first place. This absorption bottleneck can be overcome by a crystal possessing an additional spectral gap in its absorption spectrum, beyond the regular band gap, which we term the ``hypergap''. Here, we theoretically propose and experimentally demonstrate such a hypergap and the ADPM-enabled third harmonic generation in potassium chromate ${mathrm{K}}_{text{2}}{mathrm{CrO}}_{text{4}}$. Our results introduce a class of nonlinear optical materials that do not rely on lattice anisotropy or periodic poling.
{"title":"Anomalous-dispersion phase matching in a hypergap crystal","authors":"Kun Chen, Xiaolei Hu, Zhengran Wu, Xiang Guo, Zhilin Li, Ling Lü","doi":"10.1103/hnf1-vj2r","DOIUrl":"https://doi.org/10.1103/hnf1-vj2r","url":null,"abstract":"While two perfect phase-matching mechanisms exist in homogeneous single crystals, birefringent phase-matching (BPM) dominates for nonlinear optical applications. The anomalous-dispersion phase matching (ADPM), though demonstrated in gases and liquids, has not been established in crystals due to the parasitic material absorption that induces the anomalous dispersion in the first place. This absorption bottleneck can be overcome by a crystal possessing an additional spectral gap in its absorption spectrum, beyond the regular band gap, which we term the ``hypergap''. Here, we theoretically propose and experimentally demonstrate such a hypergap and the ADPM-enabled third harmonic generation in potassium chromate ${mathrm{K}}_{text{2}}{mathrm{CrO}}_{text{4}}$. Our results introduce a class of nonlinear optical materials that do not rely on lattice anisotropy or periodic poling.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"112 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147911054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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