Robust Macroscopic Schr\"odinger's Cat on a Nucleus

TL;DR

This paper introduces a fast, robust method to generate and manipulate macroscopic superposition states (spin cat states) in high-dimensional nuclear spins, enhancing quantum state control in solid-state systems.

Contribution

It presents a novel scheme leveraging quadrupolar nonlinearity for rapid, entanglement-free creation of spin cat states with high fidelity in solid-state nuclear spins.

Findings

Achieves collapse and revival of spin states two orders of magnitude faster than dephasing times.

Demonstrates arbitrary high-spin rotations using multitone control.

Enables transformation of spin coherent states into spin cat states via phase modulation.

Abstract

We propose a scheme to generate spin cat states, i.e., superpositions of maximally separated quasiclassical states on a single high-dimensional nuclear spin in a solid-state device. We exploit a strong quadrupolar nonlinearity to drive the nucleus significantly faster than usual gate sequences, achieving collapses and revivals two orders of magnitude faster than the dephasing timescale. Furthermore, these states are engineered without entanglement with an ancilla, hence, are robust against error propagation. With our multitone control, we can realize arbitrary high-spin rotations within an experimentally feasible regime, as well as transform a spin coherent state to a spin cat state using only phase modulation, opening the possibility of storing and manipulating high-fidelity cat states.