Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1408.0179 · New Journal of Physics

Constructive interference between disordered couplings enhances multiparty entanglement in quantum Heisenberg spin glass models

Utkarsh Mishra, Debraj Rakshit, R. Prabhu, Aditi Sen, Ujjwal Sen

Published Aug 25, 2016• 12 citations
arXivHTMLPDF

Abstract

Disordered systems form one of the centrestages of research in many body sciences and lead to a plethora of interesting phenomena and applications. A paradigmatic disordered system consists of a one-dimensional array of quantum spin-1/2 particles, governed by the Heisenberg spin glass Hamiltonian with natural or engineered quenched disordered couplings in an external magnetic field. These systems allow disorder-induced enhancement for bipartite and multipartite observables. Here we show that simultaneous application of independent quenched disorders results in disorder-induced enhancement, while the same is absent with individual application of the same disorders. We term the phenomenon as constructive interference and the corresponding parameter stretches as the Venus regions. Interestingly, it has only been observed for multiparty entanglement and is absent for the single- and two-party physical quantities. Introduction and background Disordered systems form one of the center-stages of research in many body sciences and lead to a plethora of interesting phenomena and applications. Presence of disorder may lead to nontrivial and counterintuitive properties as compared to their homogeneous counterparts. Prominent examples are novel quantum phases, localization, high-Tc superconductivity and disorder-induced ordering. In this work, we consider paradigmatic disordered systems consisting of a one-dimensional array of quantum spin-1/2 particles, governed by quenched disordered quantum Heisenberg Hamiltonians in external magnetic fields. The primary goal of this work is to understand the bi- and multi-partite quantum entanglement due the interplay of planer and azimuthal couplings when disorder is present in either one of them or both of them. Main results We have examined the behavior of magnetization, two-party classical as well as quantum correlations, and multipartite entanglement for the ground states of quenched disordered quantum Heisenberg spin systems for sizes ranging from five to twenty quantum spin-1/2 particles. The quenched disorder is present in the planar, or the azimuthal couplings, or in both. Our main results are the following. Firstly, in presence of the impurities in the couplings, there exist different parameter regions for different physical quantities, which show disorder-induced enhancement. We identify the parameter stretches where the phenomenon of disorder-induced enhancement corresponding to the quantities under investigation occurs for different possible cases, viz., when disorder is present in either of the interaction terms or disorder is present in both the interaction terms. Secondly, we ask a rather radical question: Is it possible to have disorder-induced enhancement of a physical quantity by the insertion of two types of disorder in a single system, while the disorders when present in the individual interaction terms do not provide any increment? We answer the question in the affirmative provided the external field strength is greater than a cut-off value. We term the phenomenon as "constructive interference" and the corresponding parameter stretches as the "Venus" regions. Interestingly, it has only been observed for multiparty entanglement and is absent for the single- and two-party physical quantities. Wider implications Firstly, the seemingly counterintuitive nature of constructive interference for a physical quantity leads us to believe that it can have implications in fundamental and application regimes. Moreover, multiparty quantum information processing tasks typically have origins in the bipartite domain. Instances where the converse occurs are few and far between, and indicate important diversions from the usual track. Secondly, a detailed knowledge on the effect of disorder on quantum correlations is highly desirable in order to assume perfect control over quantum technologies based on quantum spin magnetic systems. Thirdly, it is interesting to think about possible connections of disorder-induced enhancement with other interesting quantum phenomena such as many-body localization.

DOI
10.1088/1367-2630/18/8/083044

Related papers

Quantum correlations in quenched disordered spin models: Enhanced order from disorder by thermal fluctuations

Debasis Sadhukhan, R. Prabhu, Aditi Sen +1 more

We investigate the behavior of quantum correlations of paradigmatic quenched disordered quantum spin models, viz., the XY spin glass and random-field XY models. We show that quenched averaged quantum correlations can exhibit the order-from-disorder phenomenon for finite-size systems as well as in the thermodynamic limit. Moreover, we find that the order-from-disorder can become more pronounced in the presence of temperature by suitable tuning of the system parameters. The effects are found for entanglement measures as well as for information-theoretic quantum correlation ones, although the former show them more prominently. We also observe that the equivalence between the quenched averages and their self-averaged cousins--for classical and quantum correlations--is related to the quantum critical point in the corresponding ordered system.

arXiv:1412.8385•Physical review. E•Mar 10, 2016•13 citations

Ergodicity breaking and restoring in disordered quantum systems

Giacomo Bracci-Testasecca

Understanding the effects of disorder in quantum many-body systems is one of the central challenges of contemporary statistical physics. Its interplay with interactions and quantum fluctuations profoundly modifies the nature of quantum states and their dynamics, giving rise to phenomena such as localization, ergodicity breaking, and the emergence of complex collective behavior. This thesis presents new results on two classes of disordered quantum systems. The first part is devoted to the study of the many-body localization transition, a paradigmatic example of disorder-induced ergodicity breaking. The critical properties of the transition are investigated using a numerical renormalization-group approach, establishing a connection between its scaling behavior and that of the Anderson localization transition on tree-like graphs. The second part focuses on the zero-temperature quantum spin-glass phase of the two-dimensional bond-disordered Heisenberg model. Combining large-scale numerical simulations with a semiclassical expansion, evidence is provided for the existence of the spin-glass phase. The effective model governing the semiclassical fluctuations is further analyzed to characterize the low-energy excitation spectrum and its localization properties. Finally, the weak-disorder regime is investigated and its implications for the ferromagnetic phase are discussed. Overall, the results presented in this thesis contribute to the understanding of the effects of disorder in interacting quantum many-body systems, encompassing both localization phenomena and the collective behavior of disordered quantum magnets.

•Sep 21, 2026•0 citations

Disorder overtakes order in information concentration over quantum networks

R. Prabhu, Saurabh Pradhan, Aditi Sen +1 more

We consider different classes of quenched disordered quantum $XY$ spin chains, including a quantum $XY$ spin glass and a quantum $XY$ model with a random transverse field, and investigate the behavior of genuine multiparty entanglement in the ground states of these models. We find that there are distinct ranges of the disorder parameter that give rise to a higher genuine multiparty entanglement than in the corresponding systems without disorder: an order-from-disorder phenomenon in genuine multiparty entanglement. Moreover, we show that such a disorder-induced advantage in the genuine multiparty entanglement is useful: It is almost certainly accompanied by a order-from-disorder phenomenon for a multiport quantum dense coding capacity with the same ground state used as a multiport quantum network.

arXiv:1106.2947•Physical Review A•Oct 20, 2011•31 citations

Quantum Correlation in One Dimensional Spin Model

Sarnava Datta

We investigate the behaviour of quantum correlations (entanglement and quantum discord) for homogeneous XY model at absolute zero and at finite temperature. Study of this correlation measures of quenched disordered quantum spin models like the XY spin glass and random-field XY models is also reviewed. We show that quenched averaged quantum correlations can showcase the order-from-disorder phenomenon for finite-size systems and also when the system is in the thermodynamic limit. Though we find some regions with positive enhancement score. This order from disorder phenomena is more prominent when the system is in the finite temparature with some definite values of external parameter. We also look into correlation length. Correlation functions of ground states typically decay exponentially with the distance for quantum spin systems. In such systems, entanglement does not survive when |i-j| ≳ 3. However, quantum discord survives long lattice distances as it is not monogamous for this system. We investigate the effects of quenched disorder on quantum correlation lengths of quenched averaged entanglement and quantum discord, in the anisotropic XY spin glass chains. We realize that there is practically neither diminution nor growth in entanglement length while quantum discord length increases significantly with the introduction of quenched disorder except near factorization point. Apart from that, we also investigate the scaling behaviour of quantum entanglement and quantum discord. We find that though entanglement follows finite size scaling close to quantum phase transition, scaling can't be done for quantum discord.

•Apr 1, 2017•0 citations

Response of entanglement to annealed vis-à-vis quenched disorder in quantum spin models

Anindita Bera, Debasis Sadhukhan, Debraj Rakshit +2 more

We investigate bipartite entanglement in random quantum XY models at equilibrium. Depending on the intrinsic time scales associated with equilibration of the random parameters and measurements associated with observation of the system, we consider two distinct kinds of disorder, namely annealed and quenched. We conduct a comparative study of the effects of disorder on nearest-neighbor entanglement, when the nature of randomness changes from being annealed to quenched. We find that entanglement properties of the annealed and quenched systems are drastically different from each other. This is realized by identifying the regions of parameter space in which the nearest-neighbor state is entangled, and the regions where a disorder-induced enhancement of entanglement —order-from-disorder— is obtained. We also analyze the response of the quantum phase transition point of the ordered system with the infusion of disorder.

arXiv:1712.05226•Europhysics Letters (EPL)•Sep 12, 2019•4 citations

Spontaneous magnetization of quantum XY spin model in joint presence of quenched and annealed disorder

Anindita Bera, Debraj Rakshit, Aditi Sen +1 more

We investigate equilibrium statistical properties of the isotropic quantum XY spin-1/2 model in an external magnetic field when the interaction and field parts are subjected to quenched or annealed disorder or both. The randomness present in the system are termed annealed or quenched depending on the relation between two different time scales---the time scale associated with the equilibration of the randomness and the time of observation. Within a mean-field framework, we study the effects of disorders on spontaneous magnetization, both by perturbative and numerical techniques. Our primary interest is to understand the differences between quenched and annealed cases, and also to investigate the interplay when both of them are present in a system. We find that the magnetization survives in the presence of a unidirectional random field, irrespective of its nature, i.e., whether it is quenched or annealed. However, the field breaks the circular symmetry of the magnetization, and the system magnetizes in specific directions, parallel or transverse to the applied magnetic field. Interestingly, while the transverse magnetization is affected by the annealed disordered field, the parallel one remains unfazed by the same. Moreover, the annealed disorder present in the interaction term does not affect the system's spontaneous magnetization and the corresponding critical temperature, irrespective of the presence or absence of quenched or annealed disorder in the field term. We carry out a comparative study of these and all other different combinations of the disorders in the interaction and field terms, and point out their generic features.

arXiv:1606.01099•Physical review. B./Physical review. B•Jun 30, 2017•12 citations
Disordered systems form one of the centrestages of research in many body sciences and lead to a plethora of interesting phenomena and applications. A paradigmatic disordered system consists of a one-dimensional array of quantum spin-1/2 particles, governed by the Heisenberg spin glass Hamiltonian with natural or engineered quenched disordered couplings in an external magnetic field. These systems allow disorder-induced enhancement for bipartite and multipartite observables. Here we show that simultaneous application of independent quenched disorders results in disorder-induced enhancement, while the same is absent with individual application of the same disorders. We term the phenomenon as constructive interference and the corresponding parameter stretches as the Venus regions. Interestingly, it has only been observed for multiparty entanglement and is absent for the single- and two-party physical quantities. Introduction and background Disordered systems form one of the center-stages of research in many body sciences and lead to a plethora of interesting phenomena and applications. Presence of disorder may lead to nontrivial and counterintuitive properties as compared to their homogeneous counterparts. Prominent examples are novel quantum phases, localization, high-Tc superconductivity and disorder-induced ordering. In this work, we consider paradigmatic disordered systems consisting of a one-dimensional array of quantum spin-1/2 particles, governed by quenched disordered quantum Heisenberg Hamiltonians in external magnetic fields. The primary goal of this work is to understand the bi- and multi-partite quantum entanglement due the interplay of planer and azimuthal couplings when disorder is present in either one of them or both of them. Main results We have examined the behavior of magnetization, two-party classical as well as quantum correlations, and multipartite entanglement for the ground states of quenched disordered quantum Heisenberg spin systems for sizes ranging from five to twenty quantum spin-1/2 particles. The quenched disorder is present in the planar, or the azimuthal couplings, or in both. Our main results are the following. Firstly, in presence of the impurities in the couplings, there exist different parameter regions for different physical quantities, which show disorder-induced enhancement. We identify the parameter stretches where the phenomenon of disorder-induced enhancement corresponding to the quantities under investigation occurs for different possible cases, viz., when disorder is present in either of the interaction terms or disorder is present in both the interaction terms. Secondly, we ask a rather radical question: Is it possible to have disorder-induced enhancement of a physical quantity by the insertion of two types of disorder in a single system, while the disorders when present in the individual interaction terms do not provide any increment? We answer the question in the affirmative provided the external field strength is greater than a cut-off value. We term the phenomenon as "constructive interference" and the corresponding parameter stretches as the "Venus" regions. Interestingly, it has only been observed for multiparty entanglement and is absent for the single- and two-party physical quantities. Wider implications Firstly, the seemingly counterintuitive nature of constructive interference for a physical quantity leads us to believe that it can have implications in fundamental and application regimes. Moreover, multiparty quantum information processing tasks typically have origins in the bipartite domain. Instances where the converse occurs are few and far between, and indicate important diversions from the usual track. Secondly, a detailed knowledge on the effect of disorder on quantum correlations is highly desirable in order to assume perfect control over quantum technologies based on quantum spin magnetic systems. Thirdly, it is interesting to think about possible connections of disorder-induced enhancement with other interesting quantum phenomena such as many-body localization.
We investigate the behavior of quantum correlations of paradigmatic quenched disordered quantum spin models, viz., the XY spin glass and random-field XY models. We show that quenched averaged quantum correlations can exhibit the order-from-disorder phenomenon for finite-size systems as well as in the thermodynamic limit. Moreover, we find that the order-from-disorder can become more pronounced in the presence of temperature by suitable tuning of the system parameters. The effects are found for entanglement measures as well as for information-theoretic quantum correlation ones, although the former show them more prominently. We also observe that the equivalence between the quenched averages and their self-averaged cousins--for classical and quantum correlations--is related to the quantum critical point in the corresponding ordered system.
Understanding the effects of disorder in quantum many-body systems is one of the central challenges of contemporary statistical physics. Its interplay with interactions and quantum fluctuations profoundly modifies the nature of quantum states and their dynamics, giving rise to phenomena such as localization, ergodicity breaking, and the emergence of complex collective behavior. This thesis presents new results on two classes of disordered quantum systems. The first part is devoted to the study of the many-body localization transition, a paradigmatic example of disorder-induced ergodicity breaking. The critical properties of the transition are investigated using a numerical renormalization-group approach, establishing a connection between its scaling behavior and that of the Anderson localization transition on tree-like graphs. The second part focuses on the zero-temperature quantum spin-glass phase of the two-dimensional bond-disordered Heisenberg model. Combining large-scale numerical simulations with a semiclassical expansion, evidence is provided for the existence of the spin-glass phase. The effective model governing the semiclassical fluctuations is further analyzed to characterize the low-energy excitation spectrum and its localization properties. Finally, the weak-disorder regime is investigated and its implications for the ferromagnetic phase are discussed. Overall, the results presented in this thesis contribute to the understanding of the effects of disorder in interacting quantum many-body systems, encompassing both localization phenomena and the collective behavior of disordered quantum magnets.
We consider different classes of quenched disordered quantum XYXYXY spin chains, including a quantum XYXYXY spin glass and a quantum XYXYXY model with a random transverse field, and investigate the behavior of genuine multiparty entanglement in the ground states of these models. We find that there are distinct ranges of the disorder parameter that give rise to a higher genuine multiparty entanglement than in the corresponding systems without disorder: an order-from-disorder phenomenon in genuine multiparty entanglement. Moreover, we show that such a disorder-induced advantage in the genuine multiparty entanglement is useful: It is almost certainly accompanied by a order-from-disorder phenomenon for a multiport quantum dense coding capacity with the same ground state used as a multiport quantum network.
We investigate the behaviour of quantum correlations (entanglement and quantum discord) for homogeneous XY model at absolute zero and at finite temperature. Study of this correlation measures of quenched disordered quantum spin models like the XY spin glass and random-field XY models is also reviewed. We show that quenched averaged quantum correlations can showcase the order-from-disorder phenomenon for finite-size systems and also when the system is in the thermodynamic limit. Though we find some regions with positive enhancement score. This order from disorder phenomena is more prominent when the system is in the finite temparature with some definite values of external parameter. We also look into correlation length. Correlation functions of ground states typically decay exponentially with the distance for quantum spin systems. In such systems, entanglement does not survive when |i-j| ≳ 3. However, quantum discord survives long lattice distances as it is not monogamous for this system. We investigate the effects of quenched disorder on quantum correlation lengths of quenched averaged entanglement and quantum discord, in the anisotropic XY spin glass chains. We realize that there is practically neither diminution nor growth in entanglement length while quantum discord length increases significantly with the introduction of quenched disorder except near factorization point. Apart from that, we also investigate the scaling behaviour of quantum entanglement and quantum discord. We find that though entanglement follows finite size scaling close to quantum phase transition, scaling can't be done for quantum discord.
We investigate bipartite entanglement in random quantum XY models at equilibrium. Depending on the intrinsic time scales associated with equilibration of the random parameters and measurements associated with observation of the system, we consider two distinct kinds of disorder, namely annealed and quenched. We conduct a comparative study of the effects of disorder on nearest-neighbor entanglement, when the nature of randomness changes from being annealed to quenched. We find that entanglement properties of the annealed and quenched systems are drastically different from each other. This is realized by identifying the regions of parameter space in which the nearest-neighbor state is entangled, and the regions where a disorder-induced enhancement of entanglement —order-from-disorder— is obtained. We also analyze the response of the quantum phase transition point of the ordered system with the infusion of disorder.
We investigate equilibrium statistical properties of the isotropic quantum XY spin-1/2 model in an external magnetic field when the interaction and field parts are subjected to quenched or annealed disorder or both. The randomness present in the system are termed annealed or quenched depending on the relation between two different time scales---the time scale associated with the equilibration of the randomness and the time of observation. Within a mean-field framework, we study the effects of disorders on spontaneous magnetization, both by perturbative and numerical techniques. Our primary interest is to understand the differences between quenched and annealed cases, and also to investigate the interplay when both of them are present in a system. We find that the magnetization survives in the presence of a unidirectional random field, irrespective of its nature, i.e., whether it is quenched or annealed. However, the field breaks the circular symmetry of the magnetization, and the system magnetizes in specific directions, parallel or transverse to the applied magnetic field. Interestingly, while the transverse magnetization is affected by the annealed disordered field, the parallel one remains unfazed by the same. Moreover, the annealed disorder present in the interaction term does not affect the system's spontaneous magnetization and the corresponding critical temperature, irrespective of the presence or absence of quenched or annealed disorder in the field term. We carry out a comparative study of these and all other different combinations of the disorders in the interaction and field terms, and point out their generic features.