Academia Sinica Logo

Schrödinger cat states are quantum superposition of two macroscopically distinguishable wavepackets in the phase space. Recently such states have gained more and more importance in quantum information science. Conventional methods for deterministic preparation of Schrödinger cat states rely on isolated atomic levels [1, 2], so they only apply to atoms. In this talk I will discuss how to prepare Schrödinger cat states for any particle in a harmonic trap. That include electrons, atoms, molecules, nanoparticles, and Bose-Einstein condensates. The new quantum control scheme is called the Kapitza-Dirac (KD) blockade [3], which is a combined effect of inelastic KD scattering and destructive quantum interference. The former makes it possible to excite the motional states of trapped particles without using atomic levels; the latter stops the sequential excitation of the harmonic oscillator at a targeted eigenstate. Together, they can be used to create a plethora of non-Gaussian states such as Schrödinger cat states, Fock states, and compass states. We will conclude the talk by discussing applications of this new quantum control scheme in fundamental physics and quantum computing.