Efficient quantum computing using coherent photon conversion

Area of Science:

• Quantum Information Science
• Quantum Optics
• Nonlinear Optics

Background:

• Single photons are key quantum information carriers, enabling entanglement demonstrations.
• Current methods for preparing, processing, and measuring single photons are inefficient and probabilistic.
• Existing techniques like down-conversion produce randomly timed photons, and linear optics gates are inherently probabilistic.

Purpose of the Study:

• Introduce a deterministic process for generating and processing complex, multiquanta states for photonic quantum information.
• Present coherent photon conversion (CPC) as a versatile solution to overcome current limitations.
• Provide a full set of photonic quantum processing tools satisfying DiVincenzo criteria for scalable quantum computing.

Main Methods:

• Utilize classically pumped nonlinearities to induce coherent oscillations between orthogonal states of multiple quantum excitations.
• Employ a pumped four-wave-mixing interaction as a specific example of CPC.
• Experimentally demonstrate quantum correlations from a four-color nonlinear process using photonic crystal fibers.

Main Results:

• CPC provides a single, versatile process for a full suite of photonic quantum processing tools.
• Achieved deterministic multiqubit entanglement gates and high-quality heralded single- and multiphoton states.
• Demonstrated robust, high-efficiency detection and potential for improved down-conversion with reduced higher-order effects.

Conclusions:

• Coherent photon conversion (CPC) offers a deterministic pathway for advancing photonic quantum information applications.
• The developed tools satisfy DiVincenzo criteria, paving the way for scalable quantum computing architectures.
• The scheme is adaptable to other physical systems and can be extended using higher-order nonlinearities for multiparty mediation.