Quantum Process Tomography of an Optically-Controlled Kerr Non-linearity

Area of Science:

• Quantum Information Science
• Atomic Physics
• Nonlinear Optics

Background:

• Optical quantum information processing requires reliable methods for manipulating quantum states.
• Deterministic control over quantum states, particularly phase shifts, is crucial for building quantum technologies.
• Existing methods often lack the precision or deterministic nature required for advanced quantum computation.

Purpose of the Study:

• To experimentally characterize a novel system for optically controlled phase shifts on single-photon probe coherent states.
• To demonstrate a method for deterministic phase shifts mediated by auxiliary optical fields.
• To provide a fully characterized device for quantum information processing applications.

Main Methods:

• Utilizing electromagnetically induced transparency (EIT) in warm rubidium vapor.
• Implementing an optically triggered N-type Kerr nonlinearity to modify dispersion.
• Characterizing the system's performance using time-domain homodyne tomography.
• Applying coherent state quantum process tomography for precise state manipulation analysis.

Main Results:

• Complete experimental characterization of the optically controlled phase shift system.
• Demonstration of deterministic phase shifts on single-photon coherent states.
• Precise quantification of how the device modifies arbitrary input quantum states.

Conclusions:

• The developed system offers a robust method for deterministic optical phase shifts.
• This device is a key building block for future optical quantum information processing machines.
• The comprehensive characterization ensures reliable performance for quantum applications.