Jaydeep Kumar Basak
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Research Subjects
Jaydeep Kumar Basak has a total of 24 co-authors. Here are the top co-authors by number of shared publications:
- Gautam Sengupta
Department of Physics Indian Institute of Technology Kanpur 208016 India
19 shared publications - Mir Afrasiar
Shanghai University
14 shared publications - Himanshu Parihar
National Tsing-Hua University
8 shared publications - Dimitrios Giataganas
Department of Physics National Sun Yat-Sen University 80424 Kaohsiung Taiwan
7 shared publications - Vinayak Raj
Huzhou University
6 shared publications - Ashish Chandra
Department of Physics, Indian Institute of Technology Kanpur, Kanpur, India
5 shared publications
Latest Publications
- Open Access
- 2 November 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (11) , 9
Aspects of holographic timelike entanglement entropy in black hole backgrounds
A bstract: We study the holographic construction of timelike entanglement entropy (tEE) in black hole backgrounds in Lorentzian geometries. The holographic tEE is realized through extremal surfaces consisting of spacelike and timelike branches that encode its real and imaginary components, respectively. In the BTZ black hole, these surfaces extend into the interior of the black hole and reproduce the field-theoretic results. The analysis is further generalized to higher-dimensional AdS-Schwarzschild black holes, where the characteristics of holographic tEE are obtained with increasing size of the boundary subsystem. Besides, we also show that the boundary subsystem length diverges at a dimension-dependent critical turning point. Notably, this critical point moves closer to the black hole horizon as the dimensionality of the bulk increases. For large subsystem lengths, the finite part of the holographic tEE displays a characteristic volume-plus-area structure, with a real volume term and a complex coefficient of the area term approaching constant values at large dimensions. Besides, we also study the monotonicity of a new quantity, timelike entanglement density, which offers insights into a timelike area theorem in specific limits. Subsequently, we investigate the near-horizon dynamics in various black hole backgrounds, where the spacelike and timelike surfaces exhibit exponential growth of the form $$ {e}^{\frac{2\pi }{\beta}\Delta t} $$ with inverse black hole temperature β .- 2 November 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (11) , 9
Open AccessAspects of holographic timelike entanglement entropy in black hole backgrounds
A bstract: We study the holographic construction of timelike entanglement entropy (tEE) in black hole backgrounds in Lorentzian geometries. The holographic tEE is realized through extremal surfaces consisting of spacelike and timelike branches that encode its real and imaginary components, respectively. In the BTZ black hole, these surfaces extend into the interior of the black hole and reproduce the field-theoretic results. The analysis is further generalized to higher-dimensional AdS-Schwarzschild black holes, where the characteristics of holographic tEE are obtained with increasing size of the boundary subsystem. Besides, we also show that the boundary subsystem length diverges at a dimension-dependent critical turning point. Notably, this critical point moves closer to the black hole horizon as the dimensionality of the bulk increases. For large subsystem lengths, the finite part of the holographic tEE displays a characteristic volume-plus-area structure, with a real volume term and a complex coefficient of the area term approaching constant values at large dimensions. Besides, we also study the monotonicity of a new quantity, timelike entanglement density, which offers insights into a timelike area theorem in specific limits. Subsequently, we investigate the near-horizon dynamics in various black hole backgrounds, where the spacelike and timelike surfaces exhibit exponential growth of the form $$ {e}^{\frac{2\pi }{\beta}\Delta t} $$ with inverse black hole temperature β . - Open Access
- 6 July 2026
- Published by Oxford University Press (OUP) in Progress of Theoretical and Experimental Physics
- Vol. 2026 (9)
A New Genuine Multipartite Entanglement Measure: from Qubits to Multiboundary Wormholes
We introduce the latent entropy (L-entropy) as a novel measure to characterize the genuine multipartite entanglement in quantum systems. Our measure leverages the upper bound of reflected entropy and its maximal values attained by 2-uniform states for n-party ($n= 4,5$) and by the GHZ state for 3-party quantum systems. We demonstrate that the measure is a nonnegative, local unitary invariant function that vanishes for separable states. We then analyze its interesting characteristics in spin chain models and the Sachdev–Ye–Kitaev (SYK) model. Subsequently, we explore its implications for holography by deriving a Page-like curve for the L-entropy in the conformal field theory (CFT) dual to a multiboundary wormhole model. Furthermore, we examine the behavior of L-entropy in Haar random states, deriving analytical expressions and validating them against numerical results. In particular, we show that for $n =5$, random states approximate 2-uniform states with maximal multipartite entanglement. Furthermore, we propose a potential connection between random states and multiboundary wormhole geometries. Extending to finite-temperature systems, we introduce the multipartite thermal pure quantum (MTPQ) state, a multipartite generalization of the thermal pure quantum state, and explore its entanglement properties. By incorporating the state-dependent construction of the MTPQ state, we resolve the factorization issue in the random average of the MTPQ state, ensuring consistency with the correlation functions in the holographic dual multiboundary wormhole. Finally, we apply this construction to the multicopy SYK model and examine its multipartite entanglement structure.- 6 July 2026
- Published by Oxford University Press (OUP) in Progress of Theoretical and Experimental Physics
- Vol. 2026 (9)
Open AccessA New Genuine Multipartite Entanglement Measure: from Qubits to Multiboundary Wormholes
We introduce the latent entropy (L-entropy) as a novel measure to characterize the genuine multipartite entanglement in quantum systems. Our measure leverages the upper bound of reflected entropy and its maximal values attained by 2-uniform states for n-party ($n= 4,5$) and by the GHZ state for 3-party quantum systems. We demonstrate that the measure is a nonnegative, local unitary invariant function that vanishes for separable states. We then analyze its interesting characteristics in spin chain models and the Sachdev–Ye–Kitaev (SYK) model. Subsequently, we explore its implications for holography by deriving a Page-like curve for the L-entropy in the conformal field theory (CFT) dual to a multiboundary wormhole model. Furthermore, we examine the behavior of L-entropy in Haar random states, deriving analytical expressions and validating them against numerical results. In particular, we show that for $n =5$, random states approximate 2-uniform states with maximal multipartite entanglement. Furthermore, we propose a potential connection between random states and multiboundary wormhole geometries. Extending to finite-temperature systems, we introduce the multipartite thermal pure quantum (MTPQ) state, a multipartite generalization of the thermal pure quantum state, and explore its entanglement properties. By incorporating the state-dependent construction of the MTPQ state, we resolve the factorization issue in the random average of the MTPQ state, ensuring consistency with the correlation functions in the holographic dual multiboundary wormhole. Finally, we apply this construction to the multicopy SYK model and examine its multipartite entanglement structure. - Open Access
- 24 February 2026
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 136 (8) , 080202
L Entropy: A New Genuine Multipartite Entanglement Measure
We advance “latent entropy” ( L entropy) as a novel measure to characterize genuine multipartite entanglement in pure states, applicable to quantum systems with both finite and infinite degrees of freedom. This measure, derived from an upper bound on reflected entropy, attains its maximum for three-party Greenberger-Horne-Zeilinger states and n = 4 , 5-party 2-uniform states. We establish that it satisfies all essential properties of a genuine multipartite entanglement measure, including being a pure-state entanglement monotone. We further obtain an analog of the Page curve by analyzing the behavior of L entropy in multiboundary wormholes, emphasizing their connection to multipartite entanglement in random states. Specifically, for n = 5 , we show that random states approximate 2-uniform states, exhibiting maximal multipartite entanglement. Extending these ideas to finite temperatures, we introduce the multipartite thermal pure quantum state, a generalization of the thermal pure quantum state to multipartite systems, and demonstrate that the entanglement structure in states of the multicopy Sachdev-Ye-Kitaev model exhibits finite-temperature 2-uniform behavior.
- 24 February 2026
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 136 (8) , 080202
Open AccessL Entropy: A New Genuine Multipartite Entanglement Measure
We advance “latent entropy” ( L entropy) as a novel measure to characterize genuine multipartite entanglement in pure states, applicable to quantum systems with both finite and infinite degrees of freedom. This measure, derived from an upper bound on reflected entropy, attains its maximum for three-party Greenberger-Horne-Zeilinger states and n = 4 , 5-party 2-uniform states. We establish that it satisfies all essential properties of a genuine multipartite entanglement measure, including being a pure-state entanglement monotone. We further obtain an analog of the Page curve by analyzing the behavior of L entropy in multiboundary wormholes, emphasizing their connection to multipartite entanglement in random states. Specifically, for n = 5 , we show that random states approximate 2-uniform states, exhibiting maximal multipartite entanglement. Extending these ideas to finite temperatures, we introduce the multipartite thermal pure quantum state, a generalization of the thermal pure quantum state to multipartite systems, and demonstrate that the entanglement structure in states of the multicopy Sachdev-Ye-Kitaev model exhibits finite-temperature 2-uniform behavior.
- Open Access
L-entropy: A new genuine multipartite entanglement measure
We advance ``Latent entropy" (L-entropy) as a novel measure to characterize genuine multipartite entanglement in pure states, applicable to quantum systems with both finite and infinite degrees of freedom. This measure, derived from an upper bound on reflected entropy, attains its maximum for three-party GHZ states and $n=4,5$-party $2$-uniform states. We establish that it satisfies all essential properties of a genuine multipartite entanglement measure, including being a pure-state entanglement monotone. We further obtain an analogue of the Page curve by analyzing the behavior of L-entropy in multiboundary wormholes, emphasizing their connection to multipartite entanglement in random states. Specifically, for $n = 5$, we show that random states approximate $2$-uniform states, exhibiting maximal multipartite entanglement. Extending these ideas to finite temperatures, we introduce the Multipartite Thermal Pure Quantum (MTPQ) state, a generalization of the thermal pure quantum state to multipartite systems, and demonstrate that the entanglement structure in states of the multicopy SYK model exhibits finite-temperature $2$-uniform behavior.Open AccessL-entropy: A new genuine multipartite entanglement measure
We advance ``Latent entropy" (L-entropy) as a novel measure to characterize genuine multipartite entanglement in pure states, applicable to quantum systems with both finite and infinite degrees of freedom. This measure, derived from an upper bound on reflected entropy, attains its maximum for three-party GHZ states and $n=4,5$-party $2$-uniform states. We establish that it satisfies all essential properties of a genuine multipartite entanglement measure, including being a pure-state entanglement monotone. We further obtain an analogue of the Page curve by analyzing the behavior of L-entropy in multiboundary wormholes, emphasizing their connection to multipartite entanglement in random states. Specifically, for $n = 5$, we show that random states approximate $2$-uniform states, exhibiting maximal multipartite entanglement. Extending these ideas to finite temperatures, we introduce the Multipartite Thermal Pure Quantum (MTPQ) state, a generalization of the thermal pure quantum state to multipartite systems, and demonstrate that the entanglement structure in states of the multicopy SYK model exhibits finite-temperature $2$-uniform behavior. - Open Access
Probing the Hierarchy of Genuine Multipartite Entanglement with Generalized Latent Entropy
We introduce generalization of the recently proposed Latent Entropy (L-entropy) [1] as a refined measure of genuine multipartite entanglement (GME) in pure states of $n$-party quantum systems. Generalized L-entropy satisfies the axioms required for a valid GME measure and provides a natural ordering among $k$-uniform states maximizing for absolutely maximally entangled states (AME), effectively capturing the hierarchical structure of multipartite entanglement. We analyze the behavior of this measure for $n$-party Haar-random states and demonstrate that, in the large local-dimension limit, the maximal L-entropy saturates its upper bound for odd $n$, while for even $n$ it approaches the bound asymptotically. Furthermore, we apply this framework to examine multipartite entanglement properties of quantum states in several variants of the Sachdev--Ye--Kitaev (SYK) model, including SYK$_4$, SYK$_2$, mass-deformed SYK, sparse SYK, and $\mathcal{N}=2$ supersymmetric SYK. The results demonstrate that the generalized L-entropy serves as a sensitive probe of multipartite entanglement, revealing how deformations influence quantum entanglement structure in such strongly interacting systems.Open AccessProbing the Hierarchy of Genuine Multipartite Entanglement with Generalized Latent Entropy
We introduce generalization of the recently proposed Latent Entropy (L-entropy) [1] as a refined measure of genuine multipartite entanglement (GME) in pure states of $n$-party quantum systems. Generalized L-entropy satisfies the axioms required for a valid GME measure and provides a natural ordering among $k$-uniform states maximizing for absolutely maximally entangled states (AME), effectively capturing the hierarchical structure of multipartite entanglement. We analyze the behavior of this measure for $n$-party Haar-random states and demonstrate that, in the large local-dimension limit, the maximal L-entropy saturates its upper bound for odd $n$, while for even $n$ it approaches the bound asymptotically. Furthermore, we apply this framework to examine multipartite entanglement properties of quantum states in several variants of the Sachdev--Ye--Kitaev (SYK) model, including SYK$_4$, SYK$_2$, mass-deformed SYK, sparse SYK, and $\mathcal{N}=2$ supersymmetric SYK. The results demonstrate that the generalized L-entropy serves as a sensitive probe of multipartite entanglement, revealing how deformations influence quantum entanglement structure in such strongly interacting systems. - Open Access
- 23 May 2025
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2025 (5) , 1-34
Holographic timelike entanglement entropy in non-relativistic theories
Timelike entanglement entropy is a complex measure of information that is holographically realized by an appropriate combination of spacelike and timelike extremal surfaces. This measure is highly sensitive to Lorentz invariance breaking. In this work, we study the timelike entanglement entropy in non-relativistic theories, focusing on theories with hyperscaling violation and Lifshitz-like spatial anisotropy. The properties of the extremal surfaces, as well as the timelike entanglement entropy itself, depend heavily on the symmetry-breaking parameters of the theory. Consequently, we show that timelike entanglement can encode, to a large extent, the stability and naturalness of the theory. Furthermore, we find that timelike entanglement entropy identifies Fermi surfaces either through the logarithmic behavior of its real part or, alternatively, via its constant imaginary part, with this constant value depending on the theory’s Lifshitz exponent. This provides a novel interpretation for the imaginary component of this pseudoentropy. Additionally, we examine temporal entanglement entropy, an extension of timelike entanglement entropy to Euclidean space, and provide a comprehensive discussion of its properties in these theories.
- 23 May 2025
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2025 (5) , 1-34
Open AccessHolographic timelike entanglement entropy in non-relativistic theories
Timelike entanglement entropy is a complex measure of information that is holographically realized by an appropriate combination of spacelike and timelike extremal surfaces. This measure is highly sensitive to Lorentz invariance breaking. In this work, we study the timelike entanglement entropy in non-relativistic theories, focusing on theories with hyperscaling violation and Lifshitz-like spatial anisotropy. The properties of the extremal surfaces, as well as the timelike entanglement entropy itself, depend heavily on the symmetry-breaking parameters of the theory. Consequently, we show that timelike entanglement can encode, to a large extent, the stability and naturalness of the theory. Furthermore, we find that timelike entanglement entropy identifies Fermi surfaces either through the logarithmic behavior of its real part or, alternatively, via its constant imaginary part, with this constant value depending on the theory’s Lifshitz exponent. This provides a novel interpretation for the imaginary component of this pseudoentropy. Additionally, we examine temporal entanglement entropy, an extension of timelike entanglement entropy to Euclidean space, and provide a comprehensive discussion of its properties in these theories.
- 30 December 2024
- Published by World Scientific Pub Co Pte Ltd in International Journal of Modern Physics A
- Vol. 40 (01)
Holographic entanglement negativity for disjoint subsystems in conformal field theories with a conserved charge
In this paper, we extend a holographic construction for the entanglement negativity of two disjoint subsystems in the literature to [ ]s with a conserved charge dual to bulk [ ] geometries. This involves an algebraic sum of the areas of bulk RT surfaces for certain appropriate combinations of subsystems. In this context, we compute the holographic entanglement negativity for two disjoint subsystems with long rectangular strip geometries in [ ]s dual to bulk RN-[ ] black holes in a perturbative framework. Our results at the leading order reproduce significant features observed earlier in the literature and conform to quantum information theory, which constitute strong substantiation of our construction.
- 30 December 2024
- Published by World Scientific Pub Co Pte Ltd in International Journal of Modern Physics A
- Vol. 40 (01)
Holographic entanglement negativity for disjoint subsystems in conformal field theories with a conserved charge
In this paper, we extend a holographic construction for the entanglement negativity of two disjoint subsystems in the literature to [ ]s with a conserved charge dual to bulk [ ] geometries. This involves an algebraic sum of the areas of bulk RT surfaces for certain appropriate combinations of subsystems. In this context, we compute the holographic entanglement negativity for two disjoint subsystems with long rectangular strip geometries in [ ]s dual to bulk RN-[ ] black holes in a perturbative framework. Our results at the leading order reproduce significant features observed earlier in the literature and conform to quantum information theory, which constitute strong substantiation of our construction.
- Open Access
Holographic Timelike Entanglement Entropy in Non-relativistic Theories
Timelike entanglement entropy is a complex measure of information that is holographically realized by an appropriate combination of spacelike and timelike extremal surfaces. This measure is highly sensitive to Lorentz invariance breaking. In this work, we study the timelike entanglement entropy in non-relativistic theories, focusing on theories with hyperscaling violation and Lifshitz-like spatial anisotropy. The properties of the extremal surfaces, as well as the timelike entanglement entropy itself, depend heavily on the symmetry-breaking parameters of the theory. Consequently, we show that timelike entanglement can encode, to a large extent, the stability and naturalness of the theory. Furthermore, we find that timelike entanglement entropy identifies Fermi surfaces either through the logarithmic behavior of its real part or, alternatively, via its constant imaginary part, with this constant value depending on the theory's Lifshitz exponent. This provides a novel interpretation for the imaginary component of this pseudoentropy. Additionally, we examine temporal entanglement entropy, an extension of timelike entanglement entropy to Euclidean space, and provide a comprehensive discussion of its properties in these theories.
Open AccessHolographic Timelike Entanglement Entropy in Non-relativistic Theories
Timelike entanglement entropy is a complex measure of information that is holographically realized by an appropriate combination of spacelike and timelike extremal surfaces. This measure is highly sensitive to Lorentz invariance breaking. In this work, we study the timelike entanglement entropy in non-relativistic theories, focusing on theories with hyperscaling violation and Lifshitz-like spatial anisotropy. The properties of the extremal surfaces, as well as the timelike entanglement entropy itself, depend heavily on the symmetry-breaking parameters of the theory. Consequently, we show that timelike entanglement can encode, to a large extent, the stability and naturalness of the theory. Furthermore, we find that timelike entanglement entropy identifies Fermi surfaces either through the logarithmic behavior of its real part or, alternatively, via its constant imaginary part, with this constant value depending on the theory's Lifshitz exponent. This provides a novel interpretation for the imaginary component of this pseudoentropy. Additionally, we examine temporal entanglement entropy, an extension of timelike entanglement entropy to Euclidean space, and provide a comprehensive discussion of its properties in these theories.
- 20 November 2024
- Published by World Scientific Pub Co Pte Ltd in International Journal of Modern Physics A
- Vol. 39 (32)
Holographic entanglement negativity for disjoint subsystems in AdSd+1/CFTd
In this paper, we propose a construction to compute the holographic entanglement negativity (HEN) for bipartite mixed state configurations of two disjoint subsystems in higher-dimensional conformal field theories (CFTds) dual to bulk AdS[ ] geometries. Our proposal follows from the corresponding AdS3/CFT2 scenario and involves an algebraic sum of the areas of bulk RT surfaces for certain combinations of subsystems. By utilizing our construction, we compute the HEN at the leading order through a perturbative expansion, for such bipartite mixed states of two disjoint subsystems with long rectangular strip geometries in CFTds dual to bulk pure AdS[ ] geometries and AdS[ ]-Schwarzschild black holes.
- 20 November 2024
- Published by World Scientific Pub Co Pte Ltd in International Journal of Modern Physics A
- Vol. 39 (32)
Holographic entanglement negativity for disjoint subsystems in AdSd+1/CFTd
In this paper, we propose a construction to compute the holographic entanglement negativity (HEN) for bipartite mixed state configurations of two disjoint subsystems in higher-dimensional conformal field theories (CFTds) dual to bulk AdS[ ] geometries. Our proposal follows from the corresponding AdS3/CFT2 scenario and involves an algebraic sum of the areas of bulk RT surfaces for certain combinations of subsystems. By utilizing our construction, we compute the HEN at the leading order through a perturbative expansion, for such bipartite mixed states of two disjoint subsystems with long rectangular strip geometries in CFTds dual to bulk pure AdS[ ] geometries and AdS[ ]-Schwarzschild black holes.
- Open Access
- 25 July 2024
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2024 (7) , 1-29
Timelike entanglement entropy and phase transitions in non-conformal theories
We propose a holographic formalism for a timelike entanglement entropy in non-conformal theories. This pseudoentropy is a complex-valued measure of information, which, in holographic non-conformal theories, receives contributions from a set of spacelike surfaces and a finite timelike bulk surface with mirror symmetry. We suggest a method of merging the surfaces so that the boundary length of the subregion is exclusively specified by holography. We show that in confining theories, the surfaces can be merged in the bulk at the infrared tip of the geometry and are homologous to the boundary region. The timelike entanglement entropy receives its imaginary and real contributions from the timelike and the spacelike surfaces, respectively. Additionally, we demonstrate that in confining theories, there exists a critical length within which a connected non-trivial surface can exist, and the imaginary part of the timelike entanglement entropy is non-zero. Therefore, the timelike entanglement entropy exhibits unique behavior in confining theories, making it a probe of confinement and phase transitions. Finally, we discuss the entanglement entropy in Euclidean spacetime in confining theories and the effect of a simple analytical continuation from a spacelike subsystem to a timelike one.
- 25 July 2024
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2024 (7) , 1-29
Open AccessTimelike entanglement entropy and phase transitions in non-conformal theories
We propose a holographic formalism for a timelike entanglement entropy in non-conformal theories. This pseudoentropy is a complex-valued measure of information, which, in holographic non-conformal theories, receives contributions from a set of spacelike surfaces and a finite timelike bulk surface with mirror symmetry. We suggest a method of merging the surfaces so that the boundary length of the subregion is exclusively specified by holography. We show that in confining theories, the surfaces can be merged in the bulk at the infrared tip of the geometry and are homologous to the boundary region. The timelike entanglement entropy receives its imaginary and real contributions from the timelike and the spacelike surfaces, respectively. Additionally, we demonstrate that in confining theories, there exists a critical length within which a connected non-trivial surface can exist, and the imaginary part of the timelike entanglement entropy is non-zero. Therefore, the timelike entanglement entropy exhibits unique behavior in confining theories, making it a probe of confinement and phase transitions. Finally, we discuss the entanglement entropy in Euclidean spacetime in confining theories and the effect of a simple analytical continuation from a spacelike subsystem to a timelike one.