publications

2025

1. Multipartite entanglement vs nonlocality for two families of N-qubit states

   Sanchit Srivastava and Shohini Ghose

   Physical Review Research, 2025

   Abs DOI arXiv Bib HTML

   We analyze the relation between multipartite entanglement and genuine multipartite nonlocality, characterized by Svetlichny inequality violations, for two families of qubit states. We show that for the generalized GHZ family of states, Svetlichny inequality is not violated when the tangle is less than a threshold for any number of qubits. On the other hand, the maximal slice states always violate the Svetlichny inequality when tangle is nonzero, and the violation increases monotonically with tangle when the number of qubits is even.

   @article{srivastava2025multipartite,
     title = {Multipartite entanglement vs nonlocality for two families of {$N$}-qubit states},
     author = {Srivastava, Sanchit and Ghose, Shohini},
     journal = {Physical Review Research},
     volume = {7},
     pages = {033289},
     year = {2025},
     doi = {10.1103/btbb-p514},
   }

2. Contextuality from the vacuum

   Caroline Lima, Marı́a Rosa Preciado-Rivas, and Sanchit Srivastava

   2025

   Abs arXiv Bib HTML

   We investigate the harvesting of contextuality from the vacuum of a quantum field using Unruh-DeWitt detectors. We show that interactions with the field can endow initially non-contextual detectors with contextuality with respect to Heisenberg-Weyl measurements, as quantified by contextual fraction. The harvested contextuality correlates with the emergence of Wigner function negativity, in agreement with known equivalences between these notions. Our results establish contextuality harvesting as a fundamental phenomenon in relativistic quantum information.

   @article{srivastava2025vacuum,
     title = {Contextuality from the vacuum},
     author = {Lima, Caroline and Preciado-Rivas, Mar{\'\i}a Rosa and Srivastava, Sanchit},
     year = {2025},
   }

3. Contextuality and Chaos

   Sanchit Srivastava and Shohini Ghose

   2025

   Abs arXiv Bib HTML

   We show that contextuality, a quantum property that defies classical explanations, can serve as a signature of chaos. For a spin system undergoing chaotic dynamics, we demonstrate that violations of Bell-type inequality can effectively differentiate regular and chaotic regions of the phase space, suggesting that the nonclassicality of the system underpins signatures of chaos.

   @article{srivastava2025contextchaos,
     title = {Contextuality and Chaos},
     author = {Srivastava, Sanchit and Ghose, Shohini},
     year = {2025},
   }

2024

1. Simulating quantum chaos on a quantum computer

   Amit Anand, Sanchit Srivastava, Sayan Gangopadhyay, and 1 more author

   Scientific Reports, 2024

   Abs DOI Bib HTML

   We show that currently available noisy intermediate-scale quantum (NISQ) computers can be used for versatile quantum simulations of chaotic systems. We introduce a novel classical-quantum hybrid approach for exploring the dynamics of the chaotic quantum kicked top (QKT) on a universal quantum computer. Using a publicly accessible NISQ computer (IBMQ), we observe periodicities in the evolution of the 2-qubit QKT, as well as signatures of chaos in the time-averaged 2-qubit entanglement.

   @article{srivastava2024chaos,
     title = {Simulating quantum chaos on a quantum computer},
     author = {Anand, Amit and Srivastava, Sanchit and Gangopadhyay, Sayan and Ghose, Shohini},
     journal = {Scientific Reports},
     volume = {14},
     pages = {26890},
     year = {2024},
     doi = {10.1038/s41598-024-76448-0},
   }

2. Non-classical correlations between a quantum probe and complex quantum systems in presence of noise

   Bijoy J. Mathew, Sanchit Srivastava, and Anil Shaji

   Physics Letters A, 2024

   Abs DOI Bib HTML

   Non-classical correlations generated within a quantum probe system when it interacts with a large, macroscopic system can signal the presence of quantum features in the latter. We consider a detailed model including noise for such systems wherein a small quantum probe interacts with a large system in order to delineate the regimes with respect to coupling strengths and noise levels in which such signatures of quantumness in macroscopic systems can realistically be detected.

   @article{srivastava2024nonclassical,
     title = {Non-classical correlations between a quantum probe and complex quantum systems in presence of noise},
     author = {Mathew, Bijoy J. and Srivastava, Sanchit and Shaji, Anil},
     journal = {Physics Letters A},
     volume = {519},
     pages = {129713},
     year = {2024},
     doi = {10.1016/j.physleta.2024.129713},
   }