Professor S Sivakumar, Dean – Research, and Professor, Physics, SIAS, has co-authored a journal article titled Generation of large Fock states from coherent states using Kerr interaction and displacement, published in Physical Review A.
Technical Abstract
We discuss a scheme to generate large Fock states. The scheme involves repeatedly applying an experimentally feasible unitary transformation to convert a semiclassical state into a Fock state. The transformation combines Kerr interaction, which is a non-Gaussian operation, and pulsed coherent drives. We identify suitable parameter values (Kerr strength, pulse timings, displacement amplitude) for the physical processes to implement the transformation and generate large Fock states with near-unity fidelity. The feasibility of implementing the scheme in circuit QED architectures is discussed. The method is also suitable for generating Fock states of cavity fields.
Non-technical summary
The simple harmonic oscillator is a ubiquitous model in physics, describing everything from swinging pendulums to vibrating molecules. In the quantum world, these microscopic oscillators are restricted to specific, equally spaced energy levels—effectively forming a “ladder” of energy. An electromagnetic field confined in a cavity behaves exactly like a harmonic oscillator. But how do we force this field to climb the ladder and reach a specific, high-energy rung of our choice? Our work presents a new scheme that significantly outperforms known schemes for generating large photon states. Combining nonlinearity (where the output is not strictly proportional to the input) with displacement operations (essentially, “kicking” the oscillator in phase space), we can guide the system to much higher energy levels than previously possible. The paper discusses the mechanism behind this controlled ascent.