Two-photon interference from a bright single-photon source at telecom wavelengths

Abstract

Long-distance quantum communication relies on the ability to efficiently generate and prepare single photons at telecom wavelengths. In many applications these photons must also be indistinguishable such that they exhibit interference on a beamsplitter, which implements effective photon-photon interactions. However, deterministic generation of indistinguishable single photons with high brightness remains a challenging problem. We demonstrate two-photon interference at telecom wavelengths using an InAs/InP quantum dot in a nanophotonic cavity. The cavity enhances the quantum dot emission, resulting in a nearly Gaussian transverse mode profile with high out-coupling efficiency exceeding 36% after multi-photon correction. We also observe Purcell enhanced spontaneous emission rate up to 4. Using this source, we generate linearly polarized, high purity single photons at 1.3 μm wavelength and demonstrate the indistinguishable nature of the emission using a two-photon interference measurement, which exhibits indistinguishable visibilities of 18% without post-selection and 67% with post-selection. Our results provide a promising approach to generate bright, deterministic single photons at telecom wavelength for applications in quantum networking and quantum communication.* Email: edowaks@umd.edu 2 Single photon sources are important building blocks for optical quantum information processing [1][2][3][4]. They are essential to generate photonic quantum bits (qubits) that can travel long distances over optical fibers and interconnect distant quantum network nodes [5][6][7]. Efficient on-demand single photon sources also enable quantum computation schemes based on either linear [3, 4] or nonlinear [8] optical elements.Many applications in quantum communication require deterministic single-photon sources that emit at telecom wavelengths. Parametric down-conversion sources can operate in this wavelength range [9, 10] but provide only heralded single-photon states and cannot be easily extended to ondemand operation. In contrast, single quantum emitters provide the potential for creating ondemand single-photon sources [11, 12]. Quantum dots in III-V semiconductors are particularly promising quantum emitters that generate single photons with high indistinguishability at nearinfrared wavelengths [13][14][15][16][17][18], and are also compatible with electrical injection [19,20] and integration with nanophotonic structures [21][22][23][24]. A number of works have extended the emission of III-V quantum dots to telecom wavelengths by optimizing materials and growth parameters [25][26][27][28][29][30][31]. However, an on-demand source of indistinguishable single photons remains an outstanding challenge at telecom wavelength.In this work, we demonstrate two-photon interference from a bright single photon source at telecom wavelengths. We use a single InAs/InP quantum dot in a photonic crystal cavity to attain bright and highly polarized single-photon emission at telecom wavelengths. Rather than using the fundamental mode of the ca...

Modelling the enhancement of spectrally broadband extraction efficiency of emission from single InAs/InP quantum dots at telecommunication wavelengths

“…In that case, fabrication techniques are less mature and optimization in terms of high extraction efficiency for subsequent effective outcoupling is still an ongoing research. There only exist a very few reports on spectrally narrow extraction efficiency in InP-based microcavity systems at 1.3 µm [22], whereas the highest obtained extraction efficiencies for spectrally broad approaches are just exceeding 10% at both 1.3 µm (on GaAs) [23,24] as well as 1.55 µm (on InP) [25].…”

Two-Photon Interference from the Far-Field Emission of Chip-Integrated Cavity-Coupled Emitters

“…A number of works have reported such two-photon interference from a variety of solid-state quantum emitters such as defect centers, 10,11 dophants, 12 and quantum dots. [13][14][15][16][17][18][19][20][21][22] But these sources exhibit isotropic emission that is often difficult to collect efficiently.…”

“…[22][23][24][25] Emitters coupled to cavities can also serve as highly nonlinear devices operating at low photon numbers, 26 as well as efficient interfaces between photons and solid-state quantum memory. 27,28 The majority of the work to-date focused on a single emitter in a cavity, which can exhibit nearly perfect single photon purity and indistinguishability using resonant pumping techniques.…”

“…We couple multiple InAs/InP quantum dots that serve as efficient single photon sources 22,29,30 to independent photonic crystal cavities fabricated in close proximity on the same chip. In order to match the cavity resonances and compensate for fabrication errors, we utilize combination of nitrogen gas deposition and local thermal evaporation.…”

Silicon photonic add-drop filter for quantum emitters

“…In this work, we demonstrate a silicon photonic add-drop filter that can filter and route telecom single photons from quantum dots. We use InAs quantum dots embedded in an InP nanobeam as bright sources of single-photon emission at the telecom band [26,27]. This emission efficiently couples to a silicon waveguide using an adiabatic taper.…”