Nanomechanical state superposition in dispersive spin-mechanical systems

Speaker: Victor Montenegro
Title: Nanomechanical state superposition in dispersive spin-mechanical systems
Time:3:00pm—5:00pm, April.26.2018
Location: 818 Conference Room, Communication Building, Shahe Campus

Dr. Victor Montenegro obtained his PhD degree from University College London in the field of Physics (Quantum Optics). He is currently working as postdoctoral researcher at Pontificia Universidad Católica de Chile. His major areas of research includes: Quantum stabilization of quantum entanglement; Quantum concentration scheme in cavity quantum opto-mechanics; Interfacing of matter and light towards quantum networking applications; Theoretical aspects of quantum correlations driven by thermal environments; Topical area of quantum sudden transitions in quantum discord.

Macroscopic quantum superposition states are fundamental to test the classical-quantum boundary and present suitable candidates for quantum technologies. Although the preparations of such states have already been realized, the existing setups commonly consider external driving and resonant interactions. Motivated by these, we present a scheme to prepare non-classical states of a macroscopic mechanical object. The protocol comprises a probabilistic qubit (0 and 1 phononic states) superposition and the generation of mechanical Schroedinger’s cat states. To realize this, we have considered an open spin-mechanical quantum system via conditional displaced interaction Hamiltonian in the dispersive regime without any need for adjusting resonances. Therefore, in comparison with previous works on the matter, our proposal does not rely on any non-linearity, energy exchange nor external pumping. Our probabilistic preparation protocol is uniquely based on two steps. Firstly, we weakly evolve the spin-mechanical system for a time t, allowing us to truncate the oscillator Hilbert space up to a single phonon excitation. Subsequently, we then proceed to post-select the spin system. The latter step aims to prepare (probabilistically) any mechanical qubit superposition. Our results can be understood within the clear connection between the quantum coherence of the mechanics and the amplification of the position and momentum quadratures on average.