Abstract

When single-shot qubit readout protocols are adapted for multilevel systems, theoretical T₁ lifetime calculations often fall short of capturing the experimental lifetime trends. We identify extrinsic population dynamics as the fundamental origin of this disparity, establishing that the lifetime estimates can, in certain operating regions, be distinct from the intrinsic T₁ time. We clarify these aspects with an integrated theory to address recent measurements on spin-valley states in bilayer graphene. While confirming that phonon and Johnson noise are the dominant intrinsic sources, we show that the inclusion of extrinsic factors provides the critical match to the experimental estimates. The extrinsic factors also effectuate violations of generalized Matthiessen's rules. With an improved handle on the design space, a revised readout protocol to estimate the T₁ lifetime of the valley qubit is proposed.

Abstract

When single-shot qubit readout protocols are adapted for multilevel systems, theoretical T₁ lifetime calculations often fall short of capturing the experimental lifetime trends. We identify extrinsic population dynamics as the fundamental origin of this disparity, establishing that the lifetime estimates can, in certain operating regions, be distinct from the intrinsic T₁ time. We clarify these aspects with an integrated theory to address recent measurements on spin-valley states in bilayer graphene. While confirming that phonon and Johnson noise are the dominant intrinsic sources, we show that the inclusion of extrinsic factors provides the critical match to the experimental estimates. The extrinsic factors also effectuate violations of generalized Matthiessen's rules. With an improved handle on the design space, a revised readout protocol to estimate the T₁ lifetime of the valley qubit is proposed.

Abstract

When single-shot qubit readout protocols are adapted for multilevel systems, theoretical T₁ lifetime calculations often fall short of capturing the experimental lifetime trends. We identify extrinsic population dynamics as the fundamental origin of this disparity, establishing that the lifetime estimates can, in certain operating regions, be distinct from the intrinsic T₁ time. We clarify these aspects with an integrated theory to address recent measurements on spin-valley states in bilayer graphene. While confirming that phonon and Johnson noise are the dominant intrinsic sources, we show that the inclusion of extrinsic factors provides the critical match to the experimental estimates. The extrinsic factors also effectuate violations of generalized Matthiessen's rules. With an improved handle on the design space, a revised readout protocol to estimate the T₁ lifetime of the valley qubit is proposed.

Abstract

When single-shot qubit readout protocols are adapted for multilevel systems, theoretical T₁ lifetime calculations often fall short of capturing the experimental lifetime trends. We identify extrinsic population dynamics as the fundamental origin of this disparity, establishing that the lifetime estimates can, in certain operating regions, be distinct from the intrinsic T₁ time. We clarify these aspects with an integrated theory to address recent measurements on spin-valley states in bilayer graphene. While confirming that phonon and Johnson noise are the dominant intrinsic sources, we show that the inclusion of extrinsic factors provides the critical match to the experimental estimates. The extrinsic factors also effectuate violations of generalized Matthiessen's rules. With an improved handle on the design space, a revised readout protocol to estimate the T₁ lifetime of the valley qubit is proposed.