Exploring engineered solid-state single-photon emitters as multi-photon sources

Igor Aharonovich, Dirk Englund, Milos Toth

Joel Q. Grim, Allan S. Bracker, T. L. Reinecke +2 more

Abstract Photonic quantum science—which harnesses light-matter interactions down to the single photon level—provides advanced light sources for quantum sensing, communication, and computing. Integrating solid-state light sources on a photonic chip provides a means of creating scalable on-chip quantum networks with sophisticated optoelectronic circuitry. Extending beyond single emitters to multi-emitter systems is a frontier that offers substantial opportunities for fundamental scientific advances as well as applications that require multi-emitter quantum states. A key challenge in this endeavor is the spectral inhomogeneity of solid-state emitters, which results in non-identical emitters that cannot be interfaced with one another. This review describes recent advances in tailoring the emission properties of individual emitters and the multi-emitter demonstrations that are enabled by this control for a variety of prominent materials, as well as prospects for further development.

Lachlan J. Rogers, Kay D. Jahnke, Tokuyuki Teraji +8 more

Emitters of indistinguishable single photons are crucial for the growing field of quantum technologies. To realize scalability and increase the complexity of quantum optics technologies, multiple independent yet identical single-photon emitters are required. However, typical solid-state single-photon sources are inherently dissimilar, necessitating the use of electrical feedback or optical cavities to improve spectral overlap between distinct emitters. Here we demonstrate bright silicon vacancy (SiV−) centres in low-strain bulk diamond, which show spectral overlap of up to 91% and nearly transform-limited excitation linewidths. This is the first time that distinct single-photon emitters in the solid state have shown intrinsically identical spectral properties. Our results have impact on the application of single-photon sources for quantum optics and cryptography. In quantum optical technologies, identical emitters of indistinguishable single photons are difficult to realize due to the inherent dissimilarity of each emitting device. Here, Rogers et al.demonstrate a solid-state uniform single-photon source, which does not require external tuning of optical properties.

Marcelo Pereira de Almeida, Nor Azwa Zakaria, Jihun Cha +2 more

Yuming Wei, Shunfa Liu, Xueshi Li +12 more

J. C. Loredo

Advances in photonics will lead to breakthroughs in technology with a similar impact to that resulted from the development of electronics. At the quantum level, photons exhibit some unique features, such as non-classical correlations and bosonic bunching. The manipulation of these quanta of light foresee the construction of quantum devices capable of outperforming their classical counterparts in the purposes for which they are built. Despite a significant progress in developing quantum technologies, several unsolved issues certainly remain: Efficient quantification of quantum correlations in a system, and manipulation of multiple photons at once, are two of such hurdles to be overcome. In this thesis, we tackle these two issues and present experimental progress towards their solution. We first explore quantum entanglement between two single-photons and its effect on phases appearing on the system's wavefunction. The observed phases revealed an intimate connection between entanglement––a purely quantum phenomena––and geometric and topological structures of abstract manifolds: A special case of geometric phases was found to increase monotonically with the amount of entanglement in the system, thus serving as an alternative measure of quantum correlations. We then employed a system of three single-photons, and two concatenated entangling gates, as the basis of a quantum simulation protocol: A three-particle quantum simulator, mimicking the entangling evolution of two particles, is used to experimentally demonstrate that the overhead in measuring concurrence––a measure of two-particle entanglement––can be significantly reduced down to measuring only two observables. At this point, increasing the number of photons being handled proved extremely difficult; the low efficiency of photon sources based on parametric downconversion––the gold-standard and only source at-the-time used for multi-photon experiments––imposed a hard limit on countrates and hence the number of photons to be manipulated. We thus then focused on overcoming this obstacle: We studied a solid-state emitter and its performance as a multi-photon source. We employed a quantum dot-cavity system to show that streams of tens of indistinguishable single-photons are produced, whose temporal-to-spatial demultiplexing serves as a novel kind of multi-photon source. A three-photon source was then built and employed in the first demonstration of multi-photon interference from a solid-state source: We implemented a BosonSampling device with a source that is between one and two orders-of-magnitude more efficient than its downconversion counterpart. The main limiting factors for scaling to higher photon numbers were identified to be not intrinsic to the solid-state emitter, but determined by low detector efficiencies and the probabilistic nature of the demultiplexing scheme. Future improvements on these limitations are expected to allow the generation of sources with a higher number of single-photons, a task that has to date remained otherwise impossible.