Yulia E. Shchadilova
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Previous Organizations / Institutes
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Research Subjects
Yulia E. Shchadilova has a total of 19 co-authors. Here are the top co-authors by number of shared publications:
Alexey N. Rubtsov
Department of Physics, Lomonosov Moscow State University, Leninskie gory 1, 119991 Moscow, Russia
4 shared publications- Fabian Grusdt
Ludwig-Maximilians-Universität München
3 shared publications - Alexey M. Shakirov
Russian Quantum Center Novaya Street 100A 143025 Skolkovo Moscow Region Russia
2 shared publications Eugene Demler
Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
2 shared publicationsHiromu Ueba
2 shared publicationsMagnus Paulsson
2 shared publications
Latest Publications
- Open Access
- 7 September 2016
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 117 (11) , 113002
Quantum Dynamics of Ultracold Bose Polarons
We analyze the dynamics of Bose polarons in the vicinity of a Feshbach resonance between the impurity and host atoms. We compute the radio-frequency absorption spectra for the case when the initial state of the impurity is noninteracting and the final state is strongly interacting with the host atoms. We compare results of different theoretical approaches including a single excitation expansion, a self-consistent -matrix method, and a time-dependent coherent state approach. Our analysis reveals sharp spectral features arising from metastable states with several Bogoliubov excitations bound to the impurity atom. This surprising result of the interplay of many-body and few-body Efimov type bound state physics can only be obtained by going beyond the commonly used Fröhlich model and including quasiparticle scattering processes. Close to the resonance we find that strong fluctuations lead to a broad, incoherent absorption spectrum where no quasiparticle peak can be assigned.- 7 September 2016
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 117 (11) , 113002
Open AccessQuantum Dynamics of Ultracold Bose Polarons
We analyze the dynamics of Bose polarons in the vicinity of a Feshbach resonance between the impurity and host atoms. We compute the radio-frequency absorption spectra for the case when the initial state of the impurity is noninteracting and the final state is strongly interacting with the host atoms. We compare results of different theoretical approaches including a single excitation expansion, a self-consistent -matrix method, and a time-dependent coherent state approach. Our analysis reveals sharp spectral features arising from metastable states with several Bogoliubov excitations bound to the impurity atom. This surprising result of the interplay of many-body and few-body Efimov type bound state physics can only be obtained by going beyond the commonly used Fröhlich model and including quasiparticle scattering processes. Close to the resonance we find that strong fluctuations lead to a broad, incoherent absorption spectrum where no quasiparticle peak can be assigned. - 1 August 2016
- Published by American Physical Society (APS) in Physical Review B
- Vol. 94 (5) , 054301
Transient phases and dynamical transitions in the post-quench evolution of the generalized Bose-Anderson model
The exact description of the time evolution of open correlated quantum systems remains one of the major challenges of condensed matter theory, especially for asymptotic long times where most numerical methods fail. Here, the post-quench dynamics of the -component Bose-Anderson impurity model is studied in the limit. The equilibrium phase diagram is similar to that of the Bose-Hubbard model in that it contains local versions of Mott and Bose phases. Using a numerically exact procedure, we are able to study the real-time evolution including asymptotic long-time regimes. The formation of long-lived transient phases is observed for quench paths crossing foreign phases. For quenches inside the local Bose condensed phase, a dynamical phase transition is reported that separates the evolution towards a new equilibrium state and a regime characterized at large times by a persistent phase rotation of the order parameter. We explain how such nondecaying modes can exist in the presence of a dissipative bath. We discuss the extension of our results to the experimental relevant finite- case and their implication for the existence of nondecaying modes in generic quantum systems in the presence of a bath.- 1 August 2016
- Published by American Physical Society (APS) in Physical Review B
- Vol. 94 (5) , 054301
Transient phases and dynamical transitions in the post-quench evolution of the generalized Bose-Anderson model
The exact description of the time evolution of open correlated quantum systems remains one of the major challenges of condensed matter theory, especially for asymptotic long times where most numerical methods fail. Here, the post-quench dynamics of the -component Bose-Anderson impurity model is studied in the limit. The equilibrium phase diagram is similar to that of the Bose-Hubbard model in that it contains local versions of Mott and Bose phases. Using a numerically exact procedure, we are able to study the real-time evolution including asymptotic long-time regimes. The formation of long-lived transient phases is observed for quench paths crossing foreign phases. For quenches inside the local Bose condensed phase, a dynamical phase transition is reported that separates the evolution towards a new equilibrium state and a regime characterized at large times by a persistent phase rotation of the order parameter. We explain how such nondecaying modes can exist in the presence of a dissipative bath. We discuss the extension of our results to the experimental relevant finite- case and their implication for the existence of nondecaying modes in generic quantum systems in the presence of a bath.- 14 June 2016
- Published by American Physical Society (APS) in Physical Review E
- Vol. 93 (6) , 062122
Quantum statistical ensemble for emissive correlated systems
Relaxation dynamics of complex quantum systems with strong interactions towards the steady state is a fundamental problem in statistical mechanics. The steady state of subsystems weakly interacting with their environment is described by the canonical ensemble which assumes the probability distribution for energy to be of the Boltzmann form. The emergence of this probability distribution is ensured by the detailed balance of the transitions induced by the interaction with the environment. Here we consider relaxation of an open correlated quantum system brought into contact with a reservoir in the vacuum state. We refer to such a system as emissive since particles irreversibly evaporate into the vacuum. The steady state of the system is a statistical mixture of the stable eigenstates. We found that, despite the absence of the detailed balance, the stationary probability distribution over these eigenstates is of the Boltzmann form in each -particle sector. A quantum statistical ensemble corresponding to the steady state is characterized by different temperatures in the different sectors, in contrast to the Gibbs ensemble. We investigate the transition rates between the eigenstates to understand the emergence of the Boltzmann distribution and find their exponential dependence on the transition energy. We argue that this property of transition rates is generic for a wide class of emissive quantum many-body systems.- 14 June 2016
- Published by American Physical Society (APS) in Physical Review E
- Vol. 93 (6) , 062122
Quantum statistical ensemble for emissive correlated systems
Relaxation dynamics of complex quantum systems with strong interactions towards the steady state is a fundamental problem in statistical mechanics. The steady state of subsystems weakly interacting with their environment is described by the canonical ensemble which assumes the probability distribution for energy to be of the Boltzmann form. The emergence of this probability distribution is ensured by the detailed balance of the transitions induced by the interaction with the environment. Here we consider relaxation of an open correlated quantum system brought into contact with a reservoir in the vacuum state. We refer to such a system as emissive since particles irreversibly evaporate into the vacuum. The steady state of the system is a statistical mixture of the stable eigenstates. We found that, despite the absence of the detailed balance, the stationary probability distribution over these eigenstates is of the Boltzmann form in each -particle sector. A quantum statistical ensemble corresponding to the steady state is characterized by different temperatures in the different sectors, in contrast to the Gibbs ensemble. We investigate the transition rates between the eigenstates to understand the emergence of the Boltzmann distribution and find their exponential dependence on the transition energy. We argue that this property of transition rates is generic for a wide class of emissive quantum many-body systems.- Open Access
- 7 April 2016
- Published by American Physical Society (APS) in Physical Review A
- Vol. 93 (4) , 043606
Polaronic mass renormalization of impurities in Bose-Einstein condensates: Correlated Gaussian-wave-function approach
We propose a class of variational Gaussian wave functions to describe Fröhlich polarons at finite momenta. Our wave functions give polaron energies that are in excellent agreement with the existing Monte Carlo results for a broad range of interactions. We calculate the effective mass of polarons and find smooth crossover between weak- and intermediate-coupling strength. Effective masses that we obtain are considerably larger than those predicted by the mean-field method. A prediction based on our variational wave functions is a special pattern of correlations between host atoms that can be measured in time-of-flight experiments.
- 7 April 2016
- Published by American Physical Society (APS) in Physical Review A
- Vol. 93 (4) , 043606
Open AccessPolaronic mass renormalization of impurities in Bose-Einstein condensates: Correlated Gaussian-wave-function approach
We propose a class of variational Gaussian wave functions to describe Fröhlich polarons at finite momenta. Our wave functions give polaron energies that are in excellent agreement with the existing Monte Carlo results for a broad range of interactions. We calculate the effective mass of polarons and find smooth crossover between weak- and intermediate-coupling strength. Effective masses that we obtain are considerably larger than those predicted by the mean-field method. A prediction based on our variational wave functions is a special pattern of correlations between host atoms that can be measured in time-of-flight experiments.
- Open Access
- 17 July 2015
- Published by Springer Nature in Scientific Reports
- Vol. 5 (1) , 12124
Renormalization group approach to the Fröhlich polaron model: application to impurity-BEC problem
When a mobile impurity interacts with a many-body system, such as a phonon bath, a polaron is formed. Despite the importance of the polaron problem for a wide range of physical systems, a unified theoretical description valid for arbitrary coupling strengths is still lacking. Here we develop a renormalization group approach for analyzing a paradigmatic model of polarons, the so-called Fröhlich model and apply it to a problem of impurity atoms immersed in a Bose-Einstein condensate of ultra cold atoms. Polaron energies obtained by our method are in excellent agreement with recent diagrammatic Monte Carlo calculations for a wide range of interaction strengths. They are found to be logarithmically divergent with the ultra-violet cut-off, but physically meaningful regularized polaron energies are also presented. Moreover, we calculate the effective mass of polarons and find a smooth crossover from weak to strong coupling regimes. Possible experimental tests of our results in current experiments with ultra cold atoms are discussed.
- 17 July 2015
- Published by Springer Nature in Scientific Reports
- Vol. 5 (1) , 12124
Open AccessRenormalization group approach to the Fröhlich polaron model: application to impurity-BEC problem
When a mobile impurity interacts with a many-body system, such as a phonon bath, a polaron is formed. Despite the importance of the polaron problem for a wide range of physical systems, a unified theoretical description valid for arbitrary coupling strengths is still lacking. Here we develop a renormalization group approach for analyzing a paradigmatic model of polarons, the so-called Fröhlich model and apply it to a problem of impurity atoms immersed in a Bose-Einstein condensate of ultra cold atoms. Polaron energies obtained by our method are in excellent agreement with recent diagrammatic Monte Carlo calculations for a wide range of interaction strengths. They are found to be logarithmically divergent with the ultra-violet cut-off, but physically meaningful regularized polaron energies are also presented. Moreover, we calculate the effective mass of polarons and find a smooth crossover from weak to strong coupling regimes. Possible experimental tests of our results in current experiments with ultra cold atoms are discussed.
- Open Access
- 27 January 2015
- Published by Springer Nature in Scientific Reports
- Vol. 5 (1) , srep08005
Modeling the metastable dynamics of correlated structures
Metastable quantum dynamics of an asymmetric triangular cluster that is coupled to a reservoir is investigated. The dynamics is governed by bath-mediated transitions, which in part require a thermal activation process. The decay rate is controlled by tuning the excitation spectrum of the frustrated cluster. We use the master equation approach and construct transition operators in terms of many-body states. We analyze dynamics of observables and reveal metastability of an excited state and of a magnetically polarized ground state.
- 27 January 2015
- Published by Springer Nature in Scientific Reports
- Vol. 5 (1) , srep08005
Open AccessModeling the metastable dynamics of correlated structures
Metastable quantum dynamics of an asymmetric triangular cluster that is coupled to a reservoir is investigated. The dynamics is governed by bath-mediated transitions, which in part require a thermal activation process. The decay rate is controlled by tuning the excitation spectrum of the frustrated cluster. We use the master equation approach and construct transition operators in terms of many-body states. We analyze dynamics of observables and reveal metastability of an excited state and of a magnetically polarized ground state.
- 16 October 2014
- Published by American Physical Society (APS) in Physical Review A
- Vol. 90 (4) , 043616
Two-dimensional Bose gas of tilted dipoles: Roton instability and condensate depletion
We predict the effect of the roton instability for a two-dimensional weakly interacting gas of tilted dipoles in a single homogeneous quantum layer. Being typical for strongly correlated systems, the roton phenomena appear to occur in a weakly interacting gas. It is important that in contrast to a system of normal to the layer dipoles, breaking of the rotational symmetry for a system of tilted dipoles leads to the convergence of the condensate depletion even up to the threshold of the roton instability, with mean-field approach being valid. Predicted effects can be observed in a wide class of dipolar systems. We suggest observing predicted phenomena for systems of ultracold atoms and polar molecules in optical lattices, and estimate optimal experimental parameters.
- 16 October 2014
- Published by American Physical Society (APS) in Physical Review A
- Vol. 90 (4) , 043616
Two-dimensional Bose gas of tilted dipoles: Roton instability and condensate depletion
We predict the effect of the roton instability for a two-dimensional weakly interacting gas of tilted dipoles in a single homogeneous quantum layer. Being typical for strongly correlated systems, the roton phenomena appear to occur in a weakly interacting gas. It is important that in contrast to a system of normal to the layer dipoles, breaking of the rotational symmetry for a system of tilted dipoles leads to the convergence of the condensate depletion even up to the threshold of the roton instability, with mean-field approach being valid. Predicted effects can be observed in a wide class of dipolar systems. We suggest observing predicted phenomena for systems of ultracold atoms and polar molecules in optical lattices, and estimate optimal experimental parameters.
- 21 April 2014
- Published by American Physical Society (APS) in Physical Review B
- Vol. 89 (16)
Isotope effect in acetyleneandrotations on Cu(001)A comprehensive analysis of the elementary processes behind the scanning tunneling microscope controlled rotation of ${\mathrm{C}}_{2}{\mathrm{H}}_{2}$ and ${\mathrm{C}}_{2}{\mathrm{D}}_{2}$, isotopologues of a single acetylene molecule adsorbed on the Cu(001) surface, is given, with a focus on the isotope effects. With the help of density-functional theory we calculate the vibrational modes of ${\mathrm{C}}_{2}{\mathrm{H}}_{2}$ and ${\mathrm{C}}_{2}{\mathrm{D}}_{2}$ on Cu(001) and estimate the anharmonic couplings between them, using a simple strings-on-rods model. The probability of the elementary processes, nonlinear and combination band, is estimated using the Keldysh diagram technique. This allows us to clarify the main peculiarities and the isotope effects of the ${\mathrm{C}}_{2}{\mathrm{H}}_{2}$ and ${\mathrm{C}}_{2}{\mathrm{D}}_{2}$ on Cu(001) rotation, discovered in the pioneering work [B. C. Stipe et al., Phys. Rev. Lett. 81, 1263 (1998)], which have not been previously understood.- 21 April 2014
- Published by American Physical Society (APS) in Physical Review B
- Vol. 89 (16)
Isotope effect in acetyleneandrotations on Cu(001)A comprehensive analysis of the elementary processes behind the scanning tunneling microscope controlled rotation of ${\mathrm{C}}_{2}{\mathrm{H}}_{2}$ and ${\mathrm{C}}_{2}{\mathrm{D}}_{2}$, isotopologues of a single acetylene molecule adsorbed on the Cu(001) surface, is given, with a focus on the isotope effects. With the help of density-functional theory we calculate the vibrational modes of ${\mathrm{C}}_{2}{\mathrm{H}}_{2}$ and ${\mathrm{C}}_{2}{\mathrm{D}}_{2}$ on Cu(001) and estimate the anharmonic couplings between them, using a simple strings-on-rods model. The probability of the elementary processes, nonlinear and combination band, is estimated using the Keldysh diagram technique. This allows us to clarify the main peculiarities and the isotope effects of the ${\mathrm{C}}_{2}{\mathrm{H}}_{2}$ and ${\mathrm{C}}_{2}{\mathrm{D}}_{2}$ on Cu(001) rotation, discovered in the pioneering work [B. C. Stipe et al., Phys. Rev. Lett. 81, 1263 (1998)], which have not been previously understood.- 4 March 2014
- Published by American Physical Society (APS) in Physical Review B
- Vol. 89 (10)
Single-impurity Kondo physics at extreme particle-hole asymmetry
We study the fate of the Kondo effect with one-dimensional conduction baths at very low densities, such that the system explores the bottom of the conduction band. This can involve either finite low densities or a small number of fixed conduction electrons in a large system; i.e., the limit of large bath sizes can be taken with either fixed small density or with fixed number. We characterize the Kondo physics for such systems through the energy gain due to Kondo coupling, which is a general analog of the Kondo temperature scale, and through real-space profiles of densities and spin-spin correlation functions.
- 4 March 2014
- Published by American Physical Society (APS) in Physical Review B
- Vol. 89 (10)
Single-impurity Kondo physics at extreme particle-hole asymmetry
We study the fate of the Kondo effect with one-dimensional conduction baths at very low densities, such that the system explores the bottom of the conduction band. This can involve either finite low densities or a small number of fixed conduction electrons in a large system; i.e., the limit of large bath sizes can be taken with either fixed small density or with fixed number. We characterize the Kondo physics for such systems through the energy gain due to Kondo coupling, which is a general analog of the Kondo temperature scale, and through real-space profiles of densities and spin-spin correlation functions.
- 19 February 2014
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 112 (7) , 070601
Quantum Quenches and Work Distributions in Ultralow-Density Systems
We present results on quantum quenches in lattice systems with a fixed number of particles in a much larger number of sites. Both local and global quenches in this limit generically have power-law work distributions (``edge singularities''). We show that this regime allows for large edge singularity exponents beyond that allowed by the constraints of the usual thermodynamic limit. This large-exponent singularity has observable consequences in the time evolution, leading to a distinct intermediate power-law regime in time. We demonstrate these results first using local quantum quenches in a low-density Kondo-like system, and additionally through global and local quenches in Bose-Hubbard, Aubry-Andre, and hard-core boson systems at low densities.
- 19 February 2014
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 112 (7) , 070601
Quantum Quenches and Work Distributions in Ultralow-Density Systems
We present results on quantum quenches in lattice systems with a fixed number of particles in a much larger number of sites. Both local and global quenches in this limit generically have power-law work distributions (``edge singularities''). We show that this regime allows for large edge singularity exponents beyond that allowed by the constraints of the usual thermodynamic limit. This large-exponent singularity has observable consequences in the time evolution, leading to a distinct intermediate power-law regime in time. We demonstrate these results first using local quantum quenches in a low-density Kondo-like system, and additionally through global and local quenches in Bose-Hubbard, Aubry-Andre, and hard-core boson systems at low densities.