Coherent control of correlated nanodevices: A hybrid time-dependent numerical renormalization-group approach to periodic switching

TL;DR

This paper extends the time-dependent numerical renormalization-group (TD-NRG) method to handle periodic switching in quantum-impurity systems, enabling coherent control of strongly correlated nanodevices with new hybrid computational techniques.

Contribution

The authors develop a hybrid TD-NRG approach incorporating Chebyshev expansion to study periodic switching in correlated systems, revealing interaction-induced oscillations and their analytical characterization.

Findings

Periodic switching induces damped oscillations in the interacting resonant-level model.

Interaction strength influences the emergence and characteristics of oscillations.

Analytical estimates of oscillation frequency match numerical results.

Abstract

The time-dependent numerical renormalization-group approach (TD-NRG), originally devised for tracking the real-time dynamics of quantum-impurity systems following a single quantum quench, is extended to multiple switching events. This generalization of the TD-NRG encompasses the possibility of periodic switching, allowing for coherent control of strongly correlated systems by an external time-dependent field. To this end, we have embedded the TD-NRG in a hybrid framework that combines the outstanding capabilities of the numerical renormalization group to systematically construct the effective low-energy Hamiltonian of the system with the prowess of complementary approaches for calculating the real-time dynamics derived from this Hamiltonian. We demonstrate the power of our approach by hybridizing the TD-NRG with the Chebyshev expansion technique in order to investigate periodic switching in the interacting resonant-level model. Although the interacting model shares the same low-energy fixed point as its noninteracting counterpart, we surprisingly find the gradual emergence of damped oscillations as the interaction strength is increased. Focusing on a single quantum quench and using a strong-coupling analysis, we reveal the origin of these interaction-induced oscillations and provide an analytical estimate for their frequency. The latter agrees well with the numerical results.