Pub Date : 2020-09-09DOI: 10.1103/physreva.102.053318
Kristian Mæland, Andreas T. G. Janssønn, Jonas H. Rygh, A. Sudbø
A weakly interacting, spin-orbit coupled, ultracold, dilute Bose gas on a two-dimensional square lattice with an external Zeeman field is studied. We explore the plane and stripe wave phases of the system involving nonzero condensate momenta, which occur when the Zeeman field is below a critical value. Their excitation spectra are found using Bogoliubov theory and by two different routes. The validity of each method to obtain the excitation spectrum is discussed, and it is found that projection on the lowest single-particle band is an excellent approximation in the plane wave phase, while it is a poor approximation in the stripe wave phase. While the plane wave phase has a phonon minimum at its single condensate momentum, revealing a nonzero sound velocity of the excitations, the stripe wave phase has quadratic minima at its two condensate momenta showing zero sound velocity of the excitations. We discuss how the presence of more than one condensate momentum is essential for these differences between the two phases.
{"title":"Plane- and stripe-wave phases of a spin-orbit-coupled Bose-Einstein condensate in an optical lattice with a Zeeman field","authors":"Kristian Mæland, Andreas T. G. Janssønn, Jonas H. Rygh, A. Sudbø","doi":"10.1103/physreva.102.053318","DOIUrl":"https://doi.org/10.1103/physreva.102.053318","url":null,"abstract":"A weakly interacting, spin-orbit coupled, ultracold, dilute Bose gas on a two-dimensional square lattice with an external Zeeman field is studied. We explore the plane and stripe wave phases of the system involving nonzero condensate momenta, which occur when the Zeeman field is below a critical value. Their excitation spectra are found using Bogoliubov theory and by two different routes. The validity of each method to obtain the excitation spectrum is discussed, and it is found that projection on the lowest single-particle band is an excellent approximation in the plane wave phase, while it is a poor approximation in the stripe wave phase. While the plane wave phase has a phonon minimum at its single condensate momentum, revealing a nonzero sound velocity of the excitations, the stripe wave phase has quadratic minima at its two condensate momenta showing zero sound velocity of the excitations. We discuss how the presence of more than one condensate momentum is essential for these differences between the two phases.","PeriodicalId":8838,"journal":{"name":"arXiv: Quantum Gases","volume":"87 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75987543","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}
Pub Date : 2020-09-08DOI: 10.1103/physreva.102.033704
S. Taylor, C. Hooley
We show that, in an isolated two-level quantum system described by a time-dependent Hamiltonian, correlated noise in the Hamiltonian's parameters can lead to an arbitrarily long plateau in the state-preparation fidelity as a function of elapsed time. We explain the formation of this plateau using the Bloch-sphere representation, deriving analytical expressions for its start and end times and its height. We also briefly discuss the extent to which this phenomenon is expected to be visible in more general quantum systems with $N>2$ levels.
{"title":"Fidelity plateaus from correlated noise in isolated few-level quantum systems","authors":"S. Taylor, C. Hooley","doi":"10.1103/physreva.102.033704","DOIUrl":"https://doi.org/10.1103/physreva.102.033704","url":null,"abstract":"We show that, in an isolated two-level quantum system described by a time-dependent Hamiltonian, correlated noise in the Hamiltonian's parameters can lead to an arbitrarily long plateau in the state-preparation fidelity as a function of elapsed time. We explain the formation of this plateau using the Bloch-sphere representation, deriving analytical expressions for its start and end times and its height. We also briefly discuss the extent to which this phenomenon is expected to be visible in more general quantum systems with $N>2$ levels.","PeriodicalId":8838,"journal":{"name":"arXiv: Quantum Gases","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75909386","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}
Pub Date : 2020-09-07DOI: 10.1103/PhysRevResearch.3.013174
A. Mallick, Nana Chang, W. Maimaiti, S. Flach, A. Andreanov
We systematically construct flatbands for tight-binding models on simple Bravais lattices in space dimension $d geq 2$ in the presence of a static uniform DC field. Commensurate DC field directions yield irreducible Wannier-Stark bands in perpendicular dimension $d-1$ with $d$-dimensional eigenfunctions. The irreducible bands turn into dispersionless flatbands in the absence of nearest neighbor hoppings between lattice sites in any direction perpendicular to the DC field one. The number of commensurate directions which yield flatbands is of measure one. We arrive at a complete halt of transport, with the DC field prohibiting transport along the field direction, and the flatbands prohibiting transport in all perpendicular directions as well. The anisotropic flatband eigenstates are localizing at least factorially (faster than exponential).
{"title":"Wannier-Stark flatbands in Bravais lattices","authors":"A. Mallick, Nana Chang, W. Maimaiti, S. Flach, A. Andreanov","doi":"10.1103/PhysRevResearch.3.013174","DOIUrl":"https://doi.org/10.1103/PhysRevResearch.3.013174","url":null,"abstract":"We systematically construct flatbands for tight-binding models on simple Bravais lattices in space dimension $d geq 2$ in the presence of a static uniform DC field. Commensurate DC field directions yield irreducible Wannier-Stark bands in perpendicular dimension $d-1$ with $d$-dimensional eigenfunctions. The irreducible bands turn into dispersionless flatbands in the absence of nearest neighbor hoppings between lattice sites in any direction perpendicular to the DC field one. The number of commensurate directions which yield flatbands is of measure one. We arrive at a complete halt of transport, with the DC field prohibiting transport along the field direction, and the flatbands prohibiting transport in all perpendicular directions as well. The anisotropic flatband eigenstates are localizing at least factorially (faster than exponential).","PeriodicalId":8838,"journal":{"name":"arXiv: Quantum Gases","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81541913","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}
Pub Date : 2020-09-07DOI: 10.1103/PHYSREVA.103.043321
Takumi Yoshino, S. Furukawa, Masahito Ueda
We study the entanglement entropy and spectrum between components in binary Bose-Einstein condensates in $d$ spatial dimensions. We employ effective field theory to show that the entanglement spectrum exhibits an anomalous square-root dispersion relation in the presence of an intercomponent tunneling (a Rabi coupling) and a gapped dispersion relation in its absence. These spectral features are associated with the emergence of long-range interactions in terms of the superfluid velocity and the particle density in the entanglement Hamiltonian. Our results demonstrate that unusual long-range interactions can be emulated in a subsystem of multicomponent BECs that have only short-range interactions. We also find that for a finite Rabi coupling the entanglement entropy exhibits a volume-law scaling with subleading logarithmic corrections originating from the Nambu-Goldstone mode and the symmetry restoration for a finite volume.
{"title":"Intercomponent entanglement entropy and spectrum in binary Bose-Einstein condensates","authors":"Takumi Yoshino, S. Furukawa, Masahito Ueda","doi":"10.1103/PHYSREVA.103.043321","DOIUrl":"https://doi.org/10.1103/PHYSREVA.103.043321","url":null,"abstract":"We study the entanglement entropy and spectrum between components in binary Bose-Einstein condensates in $d$ spatial dimensions. We employ effective field theory to show that the entanglement spectrum exhibits an anomalous square-root dispersion relation in the presence of an intercomponent tunneling (a Rabi coupling) and a gapped dispersion relation in its absence. These spectral features are associated with the emergence of long-range interactions in terms of the superfluid velocity and the particle density in the entanglement Hamiltonian. Our results demonstrate that unusual long-range interactions can be emulated in a subsystem of multicomponent BECs that have only short-range interactions. We also find that for a finite Rabi coupling the entanglement entropy exhibits a volume-law scaling with subleading logarithmic corrections originating from the Nambu-Goldstone mode and the symmetry restoration for a finite volume.","PeriodicalId":8838,"journal":{"name":"arXiv: Quantum Gases","volume":"75 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86382323","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}
Pub Date : 2020-09-02DOI: 10.1103/PHYSREVRESEARCH.2.043343
K. Yamamoto, Yuto Ashida, N. Kawakami
We study how translationally invariant couplings of many-body systems and nonequilibrium baths can be used to rectify particle currents. We propose novel setups to realize bath-induced currents in nonequilibrium steady states of one-dimensional open fermionic systems. We first analyze dissipative dynamics associated with a nonreciprocal Lindblad operator and identify a class of Lindblad operators that are sufficient to acquire a nonreciprocal current. Remarkably, we show that rectification can in general occur even when a Lindblad operator is reciprocal provided that the inversion symmetry and the time-reversal symmetry of the microscopic Hamiltonian are broken. We demonstrate this new mechanism on the basis of both analytical and numerical approaches including the Rashba spin-orbit coupling and the Zeeman magnetic field. Our findings will play fundamental roles for exploring rectification phenomena in homogeneous open many-body systems.
{"title":"Rectification in nonequilibrium steady states of open many-body systems","authors":"K. Yamamoto, Yuto Ashida, N. Kawakami","doi":"10.1103/PHYSREVRESEARCH.2.043343","DOIUrl":"https://doi.org/10.1103/PHYSREVRESEARCH.2.043343","url":null,"abstract":"We study how translationally invariant couplings of many-body systems and nonequilibrium baths can be used to rectify particle currents. We propose novel setups to realize bath-induced currents in nonequilibrium steady states of one-dimensional open fermionic systems. We first analyze dissipative dynamics associated with a nonreciprocal Lindblad operator and identify a class of Lindblad operators that are sufficient to acquire a nonreciprocal current. Remarkably, we show that rectification can in general occur even when a Lindblad operator is reciprocal provided that the inversion symmetry and the time-reversal symmetry of the microscopic Hamiltonian are broken. We demonstrate this new mechanism on the basis of both analytical and numerical approaches including the Rashba spin-orbit coupling and the Zeeman magnetic field. Our findings will play fundamental roles for exploring rectification phenomena in homogeneous open many-body systems.","PeriodicalId":8838,"journal":{"name":"arXiv: Quantum Gases","volume":"608 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78957548","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}
Pub Date : 2020-08-31DOI: 10.1103/PHYSREVRESEARCH.3.013060
M. Kunimi, Kazuma Nagao, S. Goto, I. Danshita
The discrete truncated Wigner approximation (DTWA) is a powerful tool for analyzing dynamics of quantum-spin systems. Since the DTWA includes the leading order quantum corrections to a mean-field approximation, it is naturally expected that the DTWA becomes more accurate when the range of interactions of the system increases. However, quantitative corroboration of this expectation is still lacking mainly because it is generally difficult in a large system to evaluate a timescale on which the DTWA is quantitatively valid. In order to investigate how the validity timescale depends on the interaction range, we analyze dynamics of quantum spin models subjected to a sudden quench of a magnetic field by means of both DTWA and its extension including the second-order correction, which is derived from the Bogoliubov-Born-Green-Kirkwood-Yvon equation. We also develop a new formulation for calculating the second-order Renyi entropy within the framework of the DTWA. By comparing the time evolution of the Renyi entropy computed by the DTWA with that by the extension including the correction, we find that both in the one- and two-dimensional systems the validity timescale increases algebraically with the interaction range.
{"title":"Performance evaluation of the discrete truncated Wigner approximation for quench dynamics of quantum spin systems with long-range interactions","authors":"M. Kunimi, Kazuma Nagao, S. Goto, I. Danshita","doi":"10.1103/PHYSREVRESEARCH.3.013060","DOIUrl":"https://doi.org/10.1103/PHYSREVRESEARCH.3.013060","url":null,"abstract":"The discrete truncated Wigner approximation (DTWA) is a powerful tool for analyzing dynamics of quantum-spin systems. Since the DTWA includes the leading order quantum corrections to a mean-field approximation, it is naturally expected that the DTWA becomes more accurate when the range of interactions of the system increases. However, quantitative corroboration of this expectation is still lacking mainly because it is generally difficult in a large system to evaluate a timescale on which the DTWA is quantitatively valid. In order to investigate how the validity timescale depends on the interaction range, we analyze dynamics of quantum spin models subjected to a sudden quench of a magnetic field by means of both DTWA and its extension including the second-order correction, which is derived from the Bogoliubov-Born-Green-Kirkwood-Yvon equation. We also develop a new formulation for calculating the second-order Renyi entropy within the framework of the DTWA. By comparing the time evolution of the Renyi entropy computed by the DTWA with that by the extension including the correction, we find that both in the one- and two-dimensional systems the validity timescale increases algebraically with the interaction range.","PeriodicalId":8838,"journal":{"name":"arXiv: Quantum Gases","volume":"56 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84051723","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}
Pub Date : 2020-08-28DOI: 10.1103/physreva.102.053323
Christian-Marcel Schmied, P. Kevrekidis
We consider a one-dimensional trapped spin-1 Bose gas and numerically explore families of its solitonic solutions, namely antidark-dark-antidark (ADDAD), as well as dark-antidark-dark (DADD) solitary waves. Their existence and stability properties are systematically investigated within the experimentally accessible easy-plane ferromagnetic phase by means of a continuation over the atom number as well as the quadratic Zeeman energy. It is found that ADDADs are substantially more dynamically robust than DADDs. The latter are typically unstable within the examined parameter range. The dynamical evolution of both of these states is explored and the implication of their potential unstable evolution is studied. Some of the relevant observed possibilities involve, e.g., symmetry-breaking instability manifestations for the ADDAD, as well as splitting of the DADD into a right- and a left-moving dark-antidark pair with the anti-darks residing in a different component as compared to prior to the splitting. In the latter case, the structures are seen to disperse upon long-time propagation.
{"title":"Dark-antidark spinor solitons in spin-1 Bose gases","authors":"Christian-Marcel Schmied, P. Kevrekidis","doi":"10.1103/physreva.102.053323","DOIUrl":"https://doi.org/10.1103/physreva.102.053323","url":null,"abstract":"We consider a one-dimensional trapped spin-1 Bose gas and numerically explore families of its solitonic solutions, namely antidark-dark-antidark (ADDAD), as well as dark-antidark-dark (DADD) solitary waves. Their existence and stability properties are systematically investigated within the experimentally accessible easy-plane ferromagnetic phase by means of a continuation over the atom number as well as the quadratic Zeeman energy. It is found that ADDADs are substantially more dynamically robust than DADDs. The latter are typically unstable within the examined parameter range. The dynamical evolution of both of these states is explored and the implication of their potential unstable evolution is studied. Some of the relevant observed possibilities involve, e.g., symmetry-breaking instability manifestations for the ADDAD, as well as splitting of the DADD into a right- and a left-moving dark-antidark pair with the anti-darks residing in a different component as compared to prior to the splitting. In the latter case, the structures are seen to disperse upon long-time propagation.","PeriodicalId":8838,"journal":{"name":"arXiv: Quantum Gases","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76999016","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}
Pub Date : 2020-08-28DOI: 10.1103/PHYSREVRESEARCH.3.013031
P. Bonetti, A. Rucci, M. Chiofalo, V. Vuletić
The Aubry transition between sliding and pinned phases, driven by the competition between two incommensurate length scales, represents a paradigm that is applicable to a large variety of microscopically distinct systems. Despite previous theoretical studies, it remains an open question to what extent quantum effects modify the transition, or are experimentally observable. An experimental platform that can potentially reach the quantum regime has recently become available in the form of trapped laser-cooled ions subject to a periodic optical potential [A. Bylinskii, D. Gangloff, I. Counts, and V. Vuletic, Nature Materials 15, 717 (2016)]. Using Path-Integral Monte Carlo (PIMC) simulation methods, we analyze the impact of quantum tunneling on the sliding-to-pinned transition in this system, and determine the phase diagram in terms of incommensuration and potential strength. We propose new signatures of the quantum Aubry transition that are robust against thermal and finite-size effects, and that can be observed in future experiments.
{"title":"Quantum effects in the Aubry transition","authors":"P. Bonetti, A. Rucci, M. Chiofalo, V. Vuletić","doi":"10.1103/PHYSREVRESEARCH.3.013031","DOIUrl":"https://doi.org/10.1103/PHYSREVRESEARCH.3.013031","url":null,"abstract":"The Aubry transition between sliding and pinned phases, driven by the competition between two incommensurate length scales, represents a paradigm that is applicable to a large variety of microscopically distinct systems. Despite previous theoretical studies, it remains an open question to what extent quantum effects modify the transition, or are experimentally observable. An experimental platform that can potentially reach the quantum regime has recently become available in the form of trapped laser-cooled ions subject to a periodic optical potential [A. Bylinskii, D. Gangloff, I. Counts, and V. Vuletic, Nature Materials 15, 717 (2016)]. Using Path-Integral Monte Carlo (PIMC) simulation methods, we analyze the impact of quantum tunneling on the sliding-to-pinned transition in this system, and determine the phase diagram in terms of incommensuration and potential strength. We propose new signatures of the quantum Aubry transition that are robust against thermal and finite-size effects, and that can be observed in future experiments.","PeriodicalId":8838,"journal":{"name":"arXiv: Quantum Gases","volume":"61 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73889583","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}
L. Madeira, A. Cidrim, M. Hemmerling, M. Caracanhas, F. E. A. Santos, V. Bagnato, V. Bagnato
The field of quantum turbulence is related to the manifestation of turbulence in quantum fluids, such as liquid helium and ultracold gases. The concept of turbulence in quantum systems was conceived more than 70 years ago by Onsager and Feynman, but the study of turbulent ultracold gases is very recent. Although it is a young field, it already provides new approaches to the problem of turbulence. We review the advances and present status, of both theory and experiments, concerning atomic Bose-Einstein condensates (BECs). We present the difficulties of characterizing turbulence in trapped BECs, if compared to classical turbulence or turbulence in liquid helium. We summarize the challenges ahead, mostly related to the understanding of fundamental properties of quantum turbulence, including what is being done to investigate them.
{"title":"Quantum turbulence in Bose–Einstein condensates: Present status and new challenges ahead","authors":"L. Madeira, A. Cidrim, M. Hemmerling, M. Caracanhas, F. E. A. Santos, V. Bagnato, V. Bagnato","doi":"10.1116/5.0016751","DOIUrl":"https://doi.org/10.1116/5.0016751","url":null,"abstract":"The field of quantum turbulence is related to the manifestation of turbulence in quantum fluids, such as liquid helium and ultracold gases. The concept of turbulence in quantum systems was conceived more than 70 years ago by Onsager and Feynman, but the study of turbulent ultracold gases is very recent. Although it is a young field, it already provides new approaches to the problem of turbulence. We review the advances and present status, of both theory and experiments, concerning atomic Bose-Einstein condensates (BECs). We present the difficulties of characterizing turbulence in trapped BECs, if compared to classical turbulence or turbulence in liquid helium. We summarize the challenges ahead, mostly related to the understanding of fundamental properties of quantum turbulence, including what is being done to investigate them.","PeriodicalId":8838,"journal":{"name":"arXiv: Quantum Gases","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91236007","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}
Pub Date : 2020-08-26DOI: 10.1103/PHYSREVRESEARCH.2.033486
Piotr Zdybel, P. Jakubczyk
We perform a detailed analysis of the phase transition between the uniform superfluid and normal phases in spin- and mass-imbalanced Fermi mixtures. At mean-field level we demonstrate that at temperature $Tto 0$ the gradient term in the effective action can be tuned to zero for experimentally relevant sets of parameters, thus providing an avenue to realize a quantum Lifshitz point. We subsequently analyze damping processes affecting the order-parameter field across the phase transition. We show that, in the low energy limit, Landau damping occurs only in the symmetry-broken phase and affects exclusively the longitudinal component of the order-parameter field. It is however unavoidably present in the immediate vicinity of the phase transition at temperature $T=0$. We subsequently perform a renormalization-group analysis of the system in a situation, where, at mean-field level, the quantum phase transition is second order (and not multicritical). We find that, at $T$ sufficiently low, including the Landau damping term in a form derived from the microscopic action destabilizes the renormalization group flow towards the Wilson-Fisher fixed point. This signals a possible tendency to drive the transition weakly first-order by the coupling between the order-parameter fluctuations and fermionic excitations effectively captured by the Landau damping contribution to the order-parameter action.
{"title":"Quantum Lifshitz points and fluctuation-induced first-order phase transitions in imbalanced Fermi mixtures","authors":"Piotr Zdybel, P. Jakubczyk","doi":"10.1103/PHYSREVRESEARCH.2.033486","DOIUrl":"https://doi.org/10.1103/PHYSREVRESEARCH.2.033486","url":null,"abstract":"We perform a detailed analysis of the phase transition between the uniform superfluid and normal phases in spin- and mass-imbalanced Fermi mixtures. At mean-field level we demonstrate that at temperature $Tto 0$ the gradient term in the effective action can be tuned to zero for experimentally relevant sets of parameters, thus providing an avenue to realize a quantum Lifshitz point. We subsequently analyze damping processes affecting the order-parameter field across the phase transition. We show that, in the low energy limit, Landau damping occurs only in the symmetry-broken phase and affects exclusively the longitudinal component of the order-parameter field. It is however unavoidably present in the immediate vicinity of the phase transition at temperature $T=0$. We subsequently perform a renormalization-group analysis of the system in a situation, where, at mean-field level, the quantum phase transition is second order (and not multicritical). We find that, at $T$ sufficiently low, including the Landau damping term in a form derived from the microscopic action destabilizes the renormalization group flow towards the Wilson-Fisher fixed point. This signals a possible tendency to drive the transition weakly first-order by the coupling between the order-parameter fluctuations and fermionic excitations effectively captured by the Landau damping contribution to the order-parameter action.","PeriodicalId":8838,"journal":{"name":"arXiv: Quantum Gases","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74864349","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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