Pub Date : 2024-08-05DOI: 10.1103/physreva.110.023103
Michael Klaiber, Karen Z. Hatsagortsyan, Christoph H. Keitel
A relativistic analytical theory of strong-field ionization applicable across the regimes of deep tunneling up to over-the-barrier ionization (OTBI) is developed, accounting also for the bound-state polarization and the Stark shift beyond perturbation theory. The latter improvement with respect to the state-of-the-art quasiclassical theory of Perelomov-Popov-Terent'ev (PPT) for strong-field ionization is essential to describe analytically the ionization in the OTBI regime and to resolve the order-of-magnitude discrepancy of the ionization yield in the relativistic regime with respect to PPT theory that has remained unexplained since the numerical result using the Klein-Gordon equation of Hafizi et al. [Phys. Rev. Lett.118, 133201 (2017)]. The predictions of the present relativistic model, in deviation to PPT theory, are shown to be observable using ultrashort laser pulses of relativistic intensities.
{"title":"Generalized analytical description of relativistic strong-field ionization","authors":"Michael Klaiber, Karen Z. Hatsagortsyan, Christoph H. Keitel","doi":"10.1103/physreva.110.023103","DOIUrl":"https://doi.org/10.1103/physreva.110.023103","url":null,"abstract":"A relativistic analytical theory of strong-field ionization applicable across the regimes of deep tunneling up to over-the-barrier ionization (OTBI) is developed, accounting also for the bound-state polarization and the Stark shift beyond perturbation theory. The latter improvement with respect to the state-of-the-art quasiclassical theory of Perelomov-Popov-Terent'ev (PPT) for strong-field ionization is essential to describe analytically the ionization in the OTBI regime and to resolve the order-of-magnitude discrepancy of the ionization yield in the relativistic regime with respect to PPT theory that has remained unexplained since the numerical result using the Klein-Gordon equation of Hafizi <i>et al.</i> [<span>Phys. Rev. Lett.</span> <b>118</b>, 133201 (2017)]. The predictions of the present relativistic model, in deviation to PPT theory, are shown to be observable using ultrashort laser pulses of relativistic intensities.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943329","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}
Pub Date : 2024-08-05DOI: 10.1103/physreva.110.022406
Kaiming Bian, Shitao Zhang, Fei Meng, Wen Zhang, Oscar Dahlsten
Many supervised learning tasks have intrinsic symmetries, such as translational and rotational symmetry in image classifications. These symmetries can be exploited to enhance performance. We formulate the symmetry constraints into a concise mathematical form. We design two ways to adopt the constraints into the cost function, thereby shaping the cost landscape in favor of parameter choices, which respect the given symmetry. Unlike methods that alter the neural network circuit Ansatz to impose symmetry, our method only changes the classical postprocessing of gradient descent, which is simpler to implement. We call the method symmetry-guided gradient descent (SGGD). We illustrate SGGD in entanglement classification of Werner states and in two classification tasks in a two-dimensional feature space. In both cases, the results show that SGGD can accelerate the training, improve the generalization ability, and remove vanishing gradients, especially when the training data is biased.
{"title":"Symmetry-guided gradient descent for quantum neural networks","authors":"Kaiming Bian, Shitao Zhang, Fei Meng, Wen Zhang, Oscar Dahlsten","doi":"10.1103/physreva.110.022406","DOIUrl":"https://doi.org/10.1103/physreva.110.022406","url":null,"abstract":"Many supervised learning tasks have intrinsic symmetries, such as translational and rotational symmetry in image classifications. These symmetries can be exploited to enhance performance. We formulate the symmetry constraints into a concise mathematical form. We design two ways to adopt the constraints into the cost function, thereby shaping the cost landscape in favor of parameter choices, which respect the given symmetry. Unlike methods that alter the neural network circuit <i>Ansatz</i> to impose symmetry, our method only changes the classical postprocessing of gradient descent, which is simpler to implement. We call the method symmetry-guided gradient descent (SGGD). We illustrate SGGD in entanglement classification of Werner states and in two classification tasks in a two-dimensional feature space. In both cases, the results show that SGGD can accelerate the training, improve the generalization ability, and remove vanishing gradients, especially when the training data is biased.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943324","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}
Pub Date : 2024-08-05DOI: 10.1103/physreva.110.022603
Xi Cao, Jiangyu Cui, Man Hong Yung, Re-Bing Wu
Fastness and robustness are both critical in the implementation of high-fidelity gates for quantum computation, but in practice a trade-off has to be made between them. In this paper, we investigate the robust time-optimal control problem that aims at the best balance. Based on the Taylor expansion of the system in terms of uncertainty parameters, we formulate the design problem as the optimal control of an augmented finite-dimensional system at its quantum speed limit (QSL), where the robustness is graded by the order of series truncation. The gradient-descent algorithm is then introduced to sequentially seek QSLs corresponding to different orders of robustness. Numerical simulations are carried out for single-qubit systems with frequency and field amplitude uncertainties, and the obtained time-optimal control pulses can effectively suppress gate errors to the prescribed robustness order. These results provide a practical guide for selecting pulse lengths in the pulse-level compilation of quantum circuits.
{"title":"Robust control of single-qubit gates at the quantum speed limit","authors":"Xi Cao, Jiangyu Cui, Man Hong Yung, Re-Bing Wu","doi":"10.1103/physreva.110.022603","DOIUrl":"https://doi.org/10.1103/physreva.110.022603","url":null,"abstract":"Fastness and robustness are both critical in the implementation of high-fidelity gates for quantum computation, but in practice a trade-off has to be made between them. In this paper, we investigate the robust time-optimal control problem that aims at the best balance. Based on the Taylor expansion of the system in terms of uncertainty parameters, we formulate the design problem as the optimal control of an augmented finite-dimensional system at its quantum speed limit (QSL), where the robustness is graded by the order of series truncation. The gradient-descent algorithm is then introduced to sequentially seek QSLs corresponding to different orders of robustness. Numerical simulations are carried out for single-qubit systems with frequency and field amplitude uncertainties, and the obtained time-optimal control pulses can effectively suppress gate errors to the prescribed robustness order. These results provide a practical guide for selecting pulse lengths in the pulse-level compilation of quantum circuits.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943327","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}
Pub Date : 2024-08-05DOI: 10.1103/physreva.110.022803
R. Ayachitula, M. D. Anderson, C. D. McLaughlin, R. J. Knize, C. E. Mungan, M. D. Lindsay
Using Doppler-free two-photon spectroscopy of the Rb to transition in a temperature-controlled vapor cell, for both naturally occurring isotopes, we measure to high accuracy the hyperfine splittings and constants, as well as the isotope shift of the state. We lock a tunable microwave-driven electro-optic modulator sideband of the laser to an ultrastable high-finesse cavity, thus achieving microwave frequency accuracy for the relative laser tuning. The line shapes are fit with a Voigt profile to extract line centers in order to calculate the hyperfine splittings, magnetic dipole hyperfine constants, isotope shift, and hyperfine anomaly. For the hyperfine splittings of the state in and , respectively, we find and . For the hyperfine constants for the states, we find and for
{"title":"Precision measurement of hyperfine constants and isotope shift of the Rb 6S1/2 state via a two-photon transition","authors":"R. Ayachitula, M. D. Anderson, C. D. McLaughlin, R. J. Knize, C. E. Mungan, M. D. Lindsay","doi":"10.1103/physreva.110.022803","DOIUrl":"https://doi.org/10.1103/physreva.110.022803","url":null,"abstract":"Using Doppler-free two-photon spectroscopy of the Rb <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>5</mn><msub><mi>S</mi><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub></mrow></math> to <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>6</mn><msub><mi>S</mi><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub></mrow></math> transition in a temperature-controlled vapor cell, for both naturally occurring isotopes, we measure to high accuracy the hyperfine splittings and constants, as well as the isotope shift of the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>6</mn><msub><mi>S</mi><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub></mrow></math> state. We lock a tunable microwave-driven electro-optic modulator sideband of the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>993</mn><mtext>−</mtext><mi mathvariant=\"normal\">n</mi><mi mathvariant=\"normal\">m</mi></mrow></math> laser to an ultrastable high-finesse cavity, thus achieving microwave frequency accuracy for the relative laser tuning. The line shapes are fit with a Voigt profile to extract line centers in order to calculate the hyperfine splittings, magnetic dipole hyperfine constants, isotope shift, and hyperfine anomaly. For the hyperfine splittings of the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>6</mn><msub><mi>S</mi><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub></mrow></math> state in <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mmultiscripts><mi>Rb</mi><mprescripts></mprescripts><none></none><mrow><mn>85</mn></mrow></mmultiscripts></mrow></math> and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mmultiscripts><mi>Rb</mi><mprescripts></mprescripts><none></none><mrow><mn>87</mn></mrow></mmultiscripts></mrow></math>, respectively, we find <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>717.195</mn><mo>(</mo><mn>3</mn><mo>)</mo><mspace width=\"0.16em\"></mspace><mi mathvariant=\"normal\">M</mi><mi>Hz</mi></mrow></math> and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>1614.709</mn><mo>(</mo><mn>3</mn><mo>)</mo><mspace width=\"0.16em\"></mspace><mi mathvariant=\"normal\">M</mi><mi>Hz</mi></mrow></math>. For the hyperfine constants <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>A</mi></math> for the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>6</mn><msub><mi>S</mi><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub></mrow></math> states, we find <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>239.065</mn><mo>(</mo><mn>2</mn><mo>)</mo><mspace width=\"0.16em\"></mspace><mi mathvariant=\"normal\">M</mi><mi>Hz</mi></mrow></math> and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>807.355</mn><mo>(</mo><mn>2</mn><mo>)</mo><mspace width=\"0.16em\"></mspace><mi mathvariant=\"normal\">M</mi><mi>Hz</mi></mrow></math> for <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mmultiscripts><mi>Rb</mi><mprescripts></mprescripts><none></none><mrow><mn>85</mn></mrow></mm","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943328","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}
Pub Date : 2024-08-05DOI: 10.1103/physreva.110.022208
Quancheng Liu, Klaus Ziegler
The evolution of noninteracting bosons in the presence of repeated projective measurements is studied. Following the established approach, this monitored evolution is characterized by the first detected return and the first detected transition probabilities. We show that these quantities are directly related to the entanglement entropy and the entanglement spectrum of a bipartite system. Calculations with specific values for the number of bosons, the number of measurements, and the time steps between measurements reveal a sensitive and often strongly fluctuating entanglement entropy. In particular, we demonstrate that in the vicinity of special values for the time steps, the evolution of the entanglement entropy either is stationary or performs dynamical switching between two or more stationary values. In the entanglement spectrum, on the other hand, this complex behavior can be associated with level crossings, indicating that the dominant quantum states and their entanglement respond strongly to a change of the system parameters. We discuss briefly the role of time averaging to remove the fluctuations of the entanglement entropy.
{"title":"Entanglement of bosonic systems under monitored evolution","authors":"Quancheng Liu, Klaus Ziegler","doi":"10.1103/physreva.110.022208","DOIUrl":"https://doi.org/10.1103/physreva.110.022208","url":null,"abstract":"The evolution of noninteracting bosons in the presence of repeated projective measurements is studied. Following the established approach, this monitored evolution is characterized by the first detected return and the first detected transition probabilities. We show that these quantities are directly related to the entanglement entropy and the entanglement spectrum of a bipartite system. Calculations with specific values for the number of bosons, the number of measurements, and the time steps between measurements reveal a sensitive and often strongly fluctuating entanglement entropy. In particular, we demonstrate that in the vicinity of special values for the time steps, the evolution of the entanglement entropy either is stationary or performs dynamical switching between two or more stationary values. In the entanglement spectrum, on the other hand, this complex behavior can be associated with level crossings, indicating that the dominant quantum states and their entanglement respond strongly to a change of the system parameters. We discuss briefly the role of time averaging to remove the fluctuations of the entanglement entropy.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943322","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}
Pub Date : 2024-08-05DOI: 10.1103/physreva.110.022207
Junxin Chen, Benjamin B. Lane, Su Direkci, Dhruva Ganapathy, Xinghui Yin, Nergis Mavalvala, Yanbei Chen, Vivishek Sudhir
The observables of a noisy quantum system can be estimated by appropriately filtering the records of their continuous measurement. Such filtering is relevant for state estimation, and if the filter is causal, also relevant for measurement-based feedback control. It is therefore imperative that a pair of conjugate observables estimated causally satisfy the Heisenberg uncertainty principle. In this article, we prove this fact—without assuming Markovian dynamics or Gaussian noises, in the presence or absence of feedback control of the system, and where in the feedback loop (inside or outside) the measurement record is accessed. Indeed, causal estimators using the in-loop measurement record can be as precise as those using the out-of-loop record. These results clarify the role of causal estimators to non-Markovian quantum systems, restore the equanimity of in-loop and out-of-loop measurements in their estimation and control, and simplify future experiments on measurement-based quantum feedback control.
{"title":"Causal state estimation and the Heisenberg uncertainty principle","authors":"Junxin Chen, Benjamin B. Lane, Su Direkci, Dhruva Ganapathy, Xinghui Yin, Nergis Mavalvala, Yanbei Chen, Vivishek Sudhir","doi":"10.1103/physreva.110.022207","DOIUrl":"https://doi.org/10.1103/physreva.110.022207","url":null,"abstract":"The observables of a noisy quantum system can be estimated by appropriately filtering the records of their continuous measurement. Such filtering is relevant for state estimation, and if the filter is causal, also relevant for measurement-based feedback control. It is therefore imperative that a pair of conjugate observables estimated causally satisfy the Heisenberg uncertainty principle. In this article, we prove this fact—without assuming Markovian dynamics or Gaussian noises, in the presence or absence of feedback control of the system, and where in the feedback loop (inside or outside) the measurement record is accessed. Indeed, causal estimators using the in-loop measurement record can be as precise as those using the out-of-loop record. These results clarify the role of causal estimators to non-Markovian quantum systems, restore the equanimity of in-loop and out-of-loop measurements in their estimation and control, and simplify future experiments on measurement-based quantum feedback control.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943321","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}
Pub Date : 2024-08-05DOI: 10.1103/physreva.110.023303
Nejc Blaznik, Jasper Smits, Marc Duran Gutierrez, Peter van der Straten
We introduce a noninvasive imaging technique based on spin-dependent off-axis holography for spin-1 Bose-Einstein condensates. Utilizing a dual reference beam strategy, this method records two orthogonal circular polarization components of a single probe beam. The circular birefringence of spin-polarized atoms induces differing complex phase shifts in the polarization components of the light, which are reconstructed from the interference patterns captured on camera. Our approach enables spin- and density-resolved imaging of both phase and amplitude information in situ on a submillisecond timescale with minimal disturbance to the condensate. We explore the technique's efficacy under various background static fields, demonstrating its sensitivity to the quantization axis of the atoms and confirming its effectiveness.
{"title":"Imaging spinor Bose gases using off-axis holography","authors":"Nejc Blaznik, Jasper Smits, Marc Duran Gutierrez, Peter van der Straten","doi":"10.1103/physreva.110.023303","DOIUrl":"https://doi.org/10.1103/physreva.110.023303","url":null,"abstract":"We introduce a noninvasive imaging technique based on spin-dependent off-axis holography for spin-1 Bose-Einstein condensates. Utilizing a dual reference beam strategy, this method records two orthogonal circular polarization components of a single probe beam. The circular birefringence of spin-polarized atoms induces differing complex phase shifts in the polarization components of the light, which are reconstructed from the interference patterns captured on camera. Our approach enables spin- and density-resolved imaging of both phase and amplitude information <i>in situ</i> on a submillisecond timescale with minimal disturbance to the condensate. We explore the technique's efficacy under various background static fields, demonstrating its sensitivity to the quantization axis of the atoms and confirming its effectiveness.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943333","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}
Pub Date : 2024-08-05DOI: 10.1103/physreva.110.022802
Jeremy Glick, William Huntington, Daniel Heinzen
We demonstrate an approach for producing a high-flux beam of dimers by performing postnozzle seeding of a lithium beam into a supersonic helium expansion. The molecular beam has a longitudinal temperature of 13(6) mK and a continuous flux on the order of dimers/s confined within a solid angle of 0.16 sr. Monte Carlo simulations of molecular formation based on initio quantum scattering calculations are carried out and compared to the experimentally observed molecular flux. Extensions of this work could lead towards a more quantitative understanding of few-body collision processes of alkali and helium atoms.
我们展示了一种生产高通量 Li7He4 二聚体束的方法，即在超音速氦膨胀中进行锂束后喷嘴播种。分子束的纵向温度为 13(6) mK，在 0.16 sr 的固角范围内，二聚体的连续通量为 1011 个/秒。我们根据 ab initio 量子散射计算对分子的形成进行了蒙特卡罗模拟，并与实验观察到的分子通量进行了比较。这项工作的扩展可以使我们对碱原子和氦原子的少子体碰撞过程有更定量的了解。
{"title":"Cold beam of Li7He4 dimers","authors":"Jeremy Glick, William Huntington, Daniel Heinzen","doi":"10.1103/physreva.110.022802","DOIUrl":"https://doi.org/10.1103/physreva.110.022802","url":null,"abstract":"We demonstrate an approach for producing a high-flux beam of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mmultiscripts><mi>Li</mi><mprescripts></mprescripts><none></none><mn>7</mn></mmultiscripts><mmultiscripts><mi>He</mi><mprescripts></mprescripts><none></none><mn>4</mn></mmultiscripts></mrow></math> dimers by performing postnozzle seeding of a lithium beam into a supersonic helium expansion. The molecular beam has a longitudinal temperature of 13(6) mK and a continuous flux on the order of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mn>10</mn><mn>11</mn></msup></math> dimers/s confined within a solid angle of 0.16 sr. Monte Carlo simulations of molecular formation based on <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi mathvariant=\"italic\">ab</mi></mrow></math> <i>initio</i> quantum scattering calculations are carried out and compared to the experimentally observed molecular flux. Extensions of this work could lead towards a more quantitative understanding of few-body collision processes of alkali and helium atoms.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943330","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}
Pub Date : 2024-08-05DOI: 10.1103/physreva.110.023304
Sathyanarayanan Chandramouli, S. I. Mistakidis, G. C. Katsimiga, P. G. Kevrekidis
We demonstrate the controllable generation of distinct types of dispersive shock waves emerging in a quantum droplet bearing environment with the aid of steplike initial conditions. Dispersive regularization of the ensuing hydrodynamic singularities occurs due to the competition between mean-field repulsion and attractive quantum fluctuations. This interplay delineates the dominance of defocusing (hyperbolic) and focusing (elliptic) hydrodynamic phenomena being designated by the real and the imaginary speed of sound, respectively. Specifically, the symmetries of the extended Gross-Pitaevskii model lead to a three-parameter family, encompassing two densities and a relative velocity, of the underlying Riemann problem utilized herein. Surprisingly, dispersive shock waves persist across the hyperbolic-to-elliptic threshold, while a plethora of additional wave patterns arise, such as rarefaction waves, traveling dispersive shock waves, (anti)kinks, and droplet wave trains. The classification and characterization of these features are achieved by deploying Whitham modulation theory. Our results pave the way for unveiling a multitude of unexplored coherently propagating waveforms in such attractively interacting mixtures and should be detectable by current experiments.
{"title":"Dispersive shock waves in a one-dimensional droplet-bearing environment","authors":"Sathyanarayanan Chandramouli, S. I. Mistakidis, G. C. Katsimiga, P. G. Kevrekidis","doi":"10.1103/physreva.110.023304","DOIUrl":"https://doi.org/10.1103/physreva.110.023304","url":null,"abstract":"We demonstrate the controllable generation of distinct types of dispersive shock waves emerging in a quantum droplet bearing environment with the aid of steplike initial conditions. Dispersive regularization of the ensuing hydrodynamic singularities occurs due to the competition between mean-field repulsion and attractive quantum fluctuations. This interplay delineates the dominance of defocusing (hyperbolic) and focusing (elliptic) hydrodynamic phenomena being designated by the real and the imaginary speed of sound, respectively. Specifically, the symmetries of the extended Gross-Pitaevskii model lead to a three-parameter family, encompassing two densities and a relative velocity, of the underlying Riemann problem utilized herein. Surprisingly, dispersive shock waves persist across the hyperbolic-to-elliptic threshold, while a plethora of additional wave patterns arise, such as rarefaction waves, traveling dispersive shock waves, (anti)kinks, and droplet wave trains. The classification and characterization of these features are achieved by deploying Whitham modulation theory. Our results pave the way for unveiling a multitude of unexplored coherently propagating waveforms in such attractively interacting mixtures and should be detectable by current experiments.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943331","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}
Pub Date : 2024-08-05DOI: 10.1103/physreva.110.022407
Jihao Ma, Jungeng Zhou, Jiahao Huang, Chaohong Lee
One-axis twisting (OAT) and two-axis twisting (TAT) are well-known methods for achieving entanglement-enhanced quantum metrology, and their time-reversal echo offers a potent tool for approaching the Heisenberg limit even with detection noise. However, flipping the sign of interaction to implement the time-reversal echo is generally challenging. Here, we propose an echo protocol based on synthetic TAT from interaction-fixed OAT in a pseudospin-1/2 ensemble to achieve time-reversal quantum metrology. By applying modulation pulses around two different orthogonal directions, the effective TAT and its echo can be realized without changing the interaction. We demonstrate that this protocol not only outperforms the OAT echo scheme in both metrological gain and evolution time but is also robust against detection noise. Our protocol presents a TAT echo scheme that effectively avoids flipping the sign of interaction, providing a viable method for improving precision and robustness of quantum metrology.
单轴扭转（OAT）和双轴扭转（TAT）是实现纠缠增强量子计量学的著名方法，它们的时间反转回波为接近海森堡极限提供了有力的工具，即使在有探测噪声的情况下也是如此。然而，翻转相互作用的符号以实现时间反转回波通常具有挑战性。在这里，我们提出了一种基于伪ospin-1/2集合中相互作用固定 OAT 的合成 TAT 的回波协议，以实现时间反转量子计量。通过在两个不同的正交方向上应用调制脉冲，可以在不改变相互作用的情况下实现有效的 TAT 及其回波。我们证明，该协议不仅在计量增益和演化时间上优于 OAT 回波方案，而且对检测噪声也很稳健。我们的协议提出了一种有效避免翻转相互作用符号的 TAT 回波方案，为提高量子计量学的精度和稳健性提供了一种可行的方法。
{"title":"Phase amplification via synthetic two-axis-twisting echo from interaction-fixed one-axis twisting","authors":"Jihao Ma, Jungeng Zhou, Jiahao Huang, Chaohong Lee","doi":"10.1103/physreva.110.022407","DOIUrl":"https://doi.org/10.1103/physreva.110.022407","url":null,"abstract":"One-axis twisting (OAT) and two-axis twisting (TAT) are well-known methods for achieving entanglement-enhanced quantum metrology, and their time-reversal echo offers a potent tool for approaching the Heisenberg limit even with detection noise. However, flipping the sign of interaction to implement the time-reversal echo is generally challenging. Here, we propose an echo protocol based on synthetic TAT from interaction-fixed OAT in a pseudospin-1/2 ensemble to achieve time-reversal quantum metrology. By applying modulation pulses around two different orthogonal directions, the effective TAT and its echo can be realized without changing the interaction. We demonstrate that this protocol not only outperforms the OAT echo scheme in both metrological gain and evolution time but is also robust against detection noise. Our protocol presents a TAT echo scheme that effectively avoids flipping the sign of interaction, providing a viable method for improving precision and robustness of quantum metrology.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943325","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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