High-quality photonic entanglement out of a stand-alone silicon chip

Abstract

The fruitful association of quantum and integrated photonics holds the promise to produce, manipulate, and detect quantum states of light using compact and scalable systems. Integrating all the building-blocks necessary to produce high-quality photonic entanglement in the telecom wavelength range out of a single chip remains a major challenge, mainly due to the limited performance of on-chip light rejection filters. We report a stand-alone, telecom-compliant, device that integrates, on a single substrate, a nonlinear photon-pair generator and a passive pump rejection filter. Using standard channel-grid fiber demultiplexers, we demonstrate the first entanglement qualification of such a integrated circuit, showing the highest raw quantum interference visibility for time-energy entangled photons over two telecom-wavelength bands. Genuinely pure maximally entangled states can therefore be generated thanks to the high-level of noise suppression obtained with the pump filter. These results will certainly further promote the development of more advanced and scalable photonic-integrated quantum systems compliant with telecommunication standards.Quantum information science (QIS) exploits the fundamental properties of quantum physics to code and manipulate quantum states. QIS is regarded as the most promising pathway towards disruptive technologies, envisioning major improvements in processing capabilities and communication security [1,2]. However, practical implementations, such as quantum key distribution systems or quantum processors, require a large amount of compatible building-blocks [3][4][5][6]. Integrated photonics provides efficient and reliable solutions for realizing advanced quantum communication systems based on both linear and nonlinear elements [7][8][9][10][11][12][13]. Still, all these realizations face a crucial limitation as soon as on-chip suppression of photonic noise is concerned due to the substantially higher pump intensity compared to that of the photon-pairs. Most of the time, this operation is externalized, using fiber or bulk optical components, and hinders the benefit of both the compactness and stability of the whole system [14].CMOS-compatible technologies hold the promise of bringing quantum photonics one step further with optical circuits showing higher integration levels [15]. A few experiments based on this technology have been carried out to address the pump rejection challenge using on-chip solutions [16][17][18][19][20][21][22]. On-chip pump rejection has been demonstrated based on a semiconductor quantum dot integrated in a CMOS photonic circuit, but emitting out of the telecom range. The other strategies suffer from two main limitations: i) the continuous monitoring of the filter response to maintain proper performance [16][17][18], and ii) prohibitive additional interconnection losses between components [19, 20] (up to 9 dB[21]). Moreover, all these solutions have reported temporal correlation measurements for revealing the degree of indistinguishability * laurent.labonte@univ-cote...

Design of an on-Chip Room Temperature Group-IV Quantum Photonic Chem/Bio Interferometric Sensor Based on Parity Detection

“…Although it has been proven that all solutions record ~100 dB extinction, the AWG may not be favorable for scalability. While the solution proposed in [ 39 ] records both high extinction and compactness, we think it could present non-trivial limitations when applied to the case of two-colors pump, as in our scenario. Thus, we think that, due to the advantages of compact footprint, flat-top passbands, high extinction, and multiple stop-bands [ 5 ], the coupled-resonator optical waveguides can be the best solution for the quantum integrated sensor presented here.…”

“…Considerable efforts have been made to achieve on-chip high extinction filters for quantum photonics. The proposed solutions typically involve Bragg gratings [ 39 ], arrayed-waveguide gratings [ 40 ], cascaded Mach-Zehnder interferometers (MZIs) [ 41 ], and coupled-resonator optical waveguides [ 5 ], [ 42 ]. Although it has been proven that all solutions record ~100 dB extinction, the AWG may not be favorable for scalability.…”

Integrated Source of Path-Entangled Photon Pairs with Efficient Pump Self-Rejection

“…This method is very promising, with the perspective to create integrated sources of photon pairs that are compatible with the other photonic blocks necessary, for example, for quantum processors or quantum key distribution systems [ 7 , 8 ]. Such a process can be realized in integrated waveguiding structures (for example, in silicon or indium phospide (InP) platforms), which render them very suitable for building quantum photonic circuits [ 9 , 10 , 11 , 12 ].…”

“…This is often accomplished via filtering setups far larger in size that the nonlinear device producing photon pairs. Recently, there has been great interest in producing on-chip filters that reject the pump [ 9 , 12 ]. Generally, the majority of these filtering schemes are based on very precise frequency filtering allowing for transmission bands less than 1 nm wide and achieving more than 100 dB transmission of pass-band to stop-band contrast [ 9 , 12 , 13 , 14 ].…”

“…Recently, there has been great interest in producing on-chip filters that reject the pump [ 9 , 12 ]. Generally, the majority of these filtering schemes are based on very precise frequency filtering allowing for transmission bands less than 1 nm wide and achieving more than 100 dB transmission of pass-band to stop-band contrast [ 9 , 12 , 13 , 14 ]. Only recently, a theoretical proposal using photonic crystals has appeared suggesting to exploit spatial features, i.e., suppress coupling of the output mode to the pump by symmetry considerations [ 15 ].…”