Beecroft Building, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU
Dr Oana Bazavan, University of Oxford
Abstract
Higher-order nonlinear interactions on a quantum harmonic oscillator lead to increasingly nonclassical and resourceful quantum states. Some of these interactions go beyond the Gaussian formalism and, hence, serve as a resource for real-time quantum simulation of many-body models, with the potential to surpass the capabilities of classical hardware. However, studying these interactions has been challenging as they typically become exponentially weaker with increasing order. We show that hybrid systems, where an oscillator is coupled to an additional spin, provide an effective solution.
Using the motion of a trapped ion coupled to its spin, we present the experimental implementation of a new protocol relying solely on spin-dependent bosonic linear interactions to create a versatile toolkit of bosonic interactions. This includes single-mode interactions such as fourth-order squeezing (quadsqueezing) and multi-mode interactions such as beam-splitter. This technique enables higher interaction strengths compared to conventional methods, allowing for the first experimental realisation of quadsqueezing, with rates over 100 times faster than previously possible. Our approach imposes no fundamental limit on interaction order and applies universally to platforms supporting spin-dependent linear bosonic interactions. Strong higher-order nonlinear interactions unlock the study of fundamental quantum optics, quantum simulation, and computation in a hitherto unexplored regime.