Multiphoton Emission from a Single-Photon Source

Anirban Pathak

A single photon source (SPS) is very important for quantum computation. In particular, it is essential for secured quantum cryptography. But there is no perfect SPS in reality. Therefore, probabilistic SPS where probability of simultaneous emission of two, three, four and more photon is less than the emission of a single photon are used. Since classical photon always comes in bunch, the required single photon source must be nonclassical. In the well-known antibunched state the rate of simultaneous emission of two photon is less than that of single photon. But the requirement of quantum cryptography is a multiphoton version of the antibunched state or the higher order antibunched state. Recently we have reported a mathematical criterion for higher order antibunching. Here we have shown that any proposal for SPS to be used in quantum cryptography should satisfy this criterion. We have studied four wave mixing as a possible candidate of single photon source.

Matthew D. Nelson, Ravitej Uppu

Scalable quantum networks and photonic quantum technologies require single-photon sources with extremely high purity. In resonantly driven two-level systems typically employed in realizing such sources, photon purity is generally limited by multiphoton emission and residual laser scattering, traditionally treated as independent noise sources. Here, we reveal that residual laser scatter can be coherently engineered to interfere destructively with unwanted multiphoton emission, dramatically enhancing single-photon purity. Through theoretical modeling, we identify optimal excitation conditions where phase-sensitive interference harnesses noise to boost emission purity by several orders of magnitude without sacrificing brightness. These results introduce a new design paradigm for quantum light sources, where scattered light becomes a powerful resource for advancing scalable, high-purity single-photon generation in integrated photonic platforms.

Diego Martín-Cano, Caspar Groiseau, A.I. Fernandez-Dominguez +2 more

We propose a feasible single-photon source that performs over the THz frequency regime based on a single quantum polar emitter coupled to a nanocavity. We demonstrate nonclassical photon correlations showing the single photon nature of its emission as well as the nonlinear production of multiphoton pairs.

Matthew T. Rakher