Experiments in coherent state quantum computing

Program Code: 
Description of Work: 


There is considerable international research effort focused on the development of viable quantum computer technologies. Linear Optical Quantum Computing has proven to be a successful test-bed for experimental quantum computation with seminal experimental demonstrations of quantum logic operations on single photons. All of these schemes encode the quantum information on two different odes of an optical field and are known as "dual-rail" encoding schemes. A series of alternative, potentially superior, optical quantum computation schemes have been proposed based on "single-rail" encoding schemes.

Single-rail optical quantum computing is an alternative, and potentially superior, approach to optical QC. The basis states are coherent states (multi-photon states that exhibit classical optical coherence) that can be created deterministically from well-stabilised lasers. Such states are non-orthogonal, but can serve as qubits under appropriate conditions.

Such experiments will require quantum optics outside the realm of coincident measurement techniques and involve real-time quantum control, thus providing new techniques of direct relevance to our other optical quantum computation schemes. The goal of this project is to demonstrate basic quantum logic operations on nonclassical optical states suitable for single-rail encoding schemes. Successful completion of this project has the potential to demonstrate an alterative optical quantum computation scheme which may be more amenable to scale-up that existing schemes.

Description of Work:

  • Design and build the “cat-state” source;
  • Design and build the detection systems;
  • Measure the states and compare to theoretical models.