"Unlocking" spin-valley locking in zero-dimensional 2D-material heterostructures
ORAL · Invited
Abstract
There is growing interest in the physics of zero-dimensional quantum states in 2D semiconductor with hexagonal lattices such as bilayer graphene (BLG) and transitional metal dichalcogenides (TMDC). Spin-valley coupling in such heterostructures can specifically result in Kramers degeneracy, which can “lock” time-reversal symmetry protected states. These states form the basis of what is known as the Kramers qubit, which thereby promises very long relaxation times. In this talk, we will delve into our generalized strategy [1-3] to understand a wide variety of experiments under diverse conditions through a unified theoretical framework. With the insights gained, we reveal the operating conditions based on intrinsic properties and extrinsic factors the ideal conditions of operating spin-valley qubits. Moving on to the lifetimes of the spin-valley qubits, we provide a consistent interpretation of recent [4] comprehensive single shot readout measurements. By integrating theoretical predictions of pure state lifetimes with multi-state dynamics of the readout process, we bring to the fore the role of protocol-induced extrinsic factors that redistribute relaxation pathways near spin-valley qubit operating points, leading to lifetime estimates different from T1. With this missing link, we propose new interpretation of the measured lifetime trends in magnetic field and as well as comment on the applicability of a generalized Mathiessen’s rule around the level anti-crossings.
[1] A. Mukherjee and B. Muralidharan, 2D Materials, 10, 035006, (2023).
[2]. A. Mukherjee, A. Das, A. Khan and B. Muralidharan, APL Quantum, 2, 026125, (2025).
[3] A. Shandilya, S. Kapila, et. al., ACS Appl. Nano. Mat., 8, 14949, (2025).
[4] A O Denisov et al., Nat. Nano.,20, 494, (2025).
[5] R. Singh and B. Muralidharan, Comms Phys., 6, 36,(2023).
[6] A. Arora, S. Midha et.al., npj Quantum Inf., 11, 40 (2025).
*We acknowledge funding from the the Inani Chair Professorship fund through Grant No.~DO/2024-INAN/001-001, and the Department of Science and Technology, Government of India, under the National Quantum Mission through Grant no.~DST/QTC/NQM/QMD/2024/4. We also acknowledge funding from the Dhananjay Joshi Endowment award through Grant No: DO/2023-DJEF002.
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Publication:[1] A. Mukherjee and B. Muralidharan, 2D Materials, 10, 035006, (2023). [2]. A. Mukherjee, A. Das, A. Khan and B. Muralidharan, APL Quantum, 2, 026125, (2025). [3] A. Shandilya, S. Kapila, et. al., ACS Appl. Nano. Mat., 8, 14949, (2025). [4] A O Denisov et al., Nat. Nano.,20, 494, (2025). [5] R. Singh and B. Muralidharan, Comms Phys., 6, 36,(2023). [6] A. Arora, S. Midha et.al., npj Quantum Inf., 11, 40 (2025).
