Quantum light is a key resource for the development of quantum-enhanced technologies such as secure communications, quantum networks, distributed quantum computing, metrology, etc. The development of these technologies requires light sources emitting single photons in a pure quantum state as well as efficient photon-photon gates. Such sources and gates can be obtained making use of the single-photon sensitivity of an atomic transition. We study artificial atoms in the form of semiconductor quantum dots to develop building blocks for optical quantum technologies. We use the tools of opto-electronics and nanotechnology to fabricate close to ideal atom-photon interfaces, where a single artificial atom interacts with a single mode of the optical field. We show that cavity quantum electrodynamics allows to largely isolate the artificial atoms from all sources of decoherence such as charge noise and crystal vibrations. We obtain bright solid-state sources of single photons with very high quantum purity, not only in the frequency basis, but for the first time also in the photon number basis. Finally, we have made progresses toward the development of efficient two-photon gates, with devices performing as nonlinear switches at the single-photon level. Some references: High-performances quantum light sources Somaschi et al., Nature Photonics 10, 340 (2016) Grange et al, Phys. Rev. Lett. 118, 253602 (2017) Senellart, Solomon and White, Nature Nanotechnology 12, 1026 (2017) J. C. Loredo, C. Anton, et. al, arXiv:1810.05170 Scaling-up optical quantum computing Loredo et al., Optica 3, 433 (2016) Loredo et al., Phys. Rev. Lett. 118, 130503 (2017) Toward efficient photon-photon gates Giesz et al., Nat. Comm 7, 11986 (2016) De Santis et al, Nature Nanotechnology 12, 663 (2017)
Quantum light is a key resource for the development of quantum-enhanced technologies such as secure communications, quantum networks, distributed quantum computing, metrology, etc. The development of these technologies requires light sources emitting single photons in a pure quantum state as well as efficient photon-photon gates. Such sources and gates can be obtained making use of the single-photon sensitivity of an atomic transition. We study artificial atoms in the form of semiconductor quantum dots to develop building blocks for optical quantum technologies. We use the tools of opto-electronics and nanotechnology to fabricate close to ideal atom-photon interfaces, where a single artificial atom interacts with a single mode of the optical field. We show that cavity quantum electrodynamics allows to largely isolate the artificial atoms from all sources of decoherence such as charge noise and crystal vibrations. We obtain bright solid-state sources of single photons with very high quantum purity, not only in the frequency basis, but for the first time also in the photon number basis. Finally, we have made progresses toward the development of efficient two-photon gates, with devices performing as nonlinear switches at the single-photon level. Some references: High-performances quantum light sources Somaschi et al., Nature Photonics 10, 340 (2016) Grange et al, Phys. Rev. Lett. 118, 253602 (2017) Senellart, Solomon and White, Nature Nanotechnology 12, 1026 (2017) J. C. Loredo, C. Anton, et. al, arXiv:1810.05170 Scaling-up optical quantum computing Loredo et al., Optica 3, 433 (2016) Loredo et al., Phys. Rev. Lett. 118, 130503 (2017) Toward efficient photon-photon gates Giesz et al., Nat. Comm 7, 11986 (2016) De Santis et al, Nature Nanotechnology 12, 663 (2017)
The ability to generate and manipulate light in pure quantum states is central to the development of quantum enhanced technologies, be it for optical quantum computing or for quantum secure communications. Recently, artificial atoms in the form of semiconductor quantum dots have emerged as an excellent platform to develop efficient components for optical quantum technologies. Using the tools of cavity quantum electrodynamics to harness the quantum light emission and to reduce the decoherence phenomena, single photon wavepackets with very high quantum purity can now be generated. This new generation of devices show unprecedented efficiency and allows scaling-up linear quantum optical technologies [3,4]. The high quality of the artificial atoms also allows to observe new phenomena, such as the generation of light pulses in a pure quantum superposition in the photon number basis [5], or to explore optical non-linearities at the single photon level [6] [1] N. Somaschi, et al. Nature Photonics, 10, 340 (2016) [2] P Senellart, G Solomon, A White, Nature Nanotechnology 12 (11), (2017) [3] C Antón, et al., Optica 6 (12), 1471-1477 (2019) [4] D. Istrati, arXiv 1912.04375 [5] J. C. Loredo, C. Antón, et., Nature Photonics 13 (11), 803 (2019) [6] L. De Santis, et al, Nature Nanotechnology 12, 663 (2017)
Semiconductor quantum dots (QDs) are promising artificial atoms for quantum information processing: they can generate single photons flying quantum bits; they show single photon sensitivity promising to develop quantum gates and the spin of a carrier in a QD can be a quantum memory. The scalability of a quantum network requires efficient interfaces between stationary and flying quantum bits. In the last few years, our group has made important progresses in this direction using cavity quantum electrodynamics. With a deterministic positioning of a single QD in a microcavity, we control the QD spontaneous emission on demand [1]. With such technique highly efficient single photon sources with brightness as large as 80% are demonstrated [2]. By minimizing the charge noise around the QD in a gated structure [3], we demonstrate the generation of fully indistinguishable photon. The source brightness is shown to exceed by one or two orders of magnitude the one of a parametric down-conversion source of same quality [4]. Symmetrically, these devices perform as excellent interfaces between a flying quantum bit and a stationary one, where coherent control of a quantum bit can be done when only few photons [5]. References [1] A. Dousse, et al. , Phys. Rev. Lett. 101, 267404 (2008) [2] O. Gazzano, et al. , Nature Communications 4, 1425 (2013) [3] A. Nowak. et al., Nature Communications 5, 3240 (2014) [4] N. Somaschi, et al. Nature Photonics 10.1038/nphoton.2016.23 (2016). [5] V. Giesz, et al., Nature Communications doi:10.1038/ncomms11986 (2016)
Semiconductor quantum dots have emerged as an excellent platform for quantum light generation, providing quantum pure single photon wavepackets with unparalleled efficiency. These devices have started to accelerate the development of optical quantum technologies – notably in the field of optical quantum computing. In this talk, I will discuss our progresses toward the deterministic source, the use of these sources for the generation of linear cluster states and the generation of quantum light state using spontaneous emission as a resource for entanglement in the photon number basis.
Quantum light and in particular single photons have become essential resources for a growing number of quantum applications including quantum computing, quantum key distribution and quantum metrology. Solid-state atomlike systems such as semiconductor quantum dots and color defects in crystals have become the hallmark of highly pure single photon emitters in the past two decades. A particular interest has been developed in nanocrystal quantum dots (NQDs) and color centers in diamond as potential compact room-temperature emitters. There are however several challenges that inhibit the use of such sources in current technologies including low photon extraction efficiency, low emission rates and relatively low single photon purities. In this work we will review our efforts in overcoming these technical difficulties using several complementary methods including designing several nanoantenna devices that enhance the directionality and emission rate of the nanoemitter. In addition, we developed several temporal heralding techniques to overcome the hurdle of low single photon purity in NQDs in an effort to produce a highly pure, bright and efficient single photon source on-chip.
Optical quantum technology needs efficient sources for non-classical light. Solid-state emitters provide excellent mode purity, high brightness, and often also stable operation up to room temperature. At the same time the spin of individual impurities can be entangled with emitted photons. Nano-photonic structures can dramatically enhance the photon emission efficiency and thus the yield of quantum information processing tasks involving photons. One example is a node of a quantum repeater network. In this presentation we address the issue of enhanced photon collection from optically active defects in the solid-state such as diamond [1] or two-dimensional material [2]. We briefly introduce the emitters and then describe recent experiments where we couple them to dielectric/plasmonic antennas [3] and to SiO2/Si light collecting structures [4]. References [1] “Fiber-Coupled Diamond Micro-Waveguides toward an Efficient Quantum Interface for Spin Defect Centers”, M. Fujiwara, O. Neitzke, T. Schröder, A. W. Schell, J. Wolters, J. Zheng, S. Mouradian, M. Almoktar, S. Takeuchi, D. Englund, and O. Benson, ACS Omega 2, 7194-7202 (2017) [2] “Photodynamics of quantum emitters in hexagonal boron nitride revealed by low-temperature spectroscopy“, B. Sontheimer, M. Braun, N. Nikolay, N. Sadzak, I. Aharonovich, and Oliver Benson, Phys. Rev B 96, 121202(R) (2017). [3] “Accurate placement of single nano particles on opaque conductive structures“, N. Nikolay, N. Sadzak, A. Dohms, B. Lubotzky, H. Abudayyeh, R. Rapaport, and O. Benson, Appl. Phys. Lett, accepted (2018); arXiv:1807.10605 [4] “Fine-tuning of whispering gallery modes in on-chip silica microdisk resonators within a full spectral range“, R. Henze, C. Pyrlik, A. Thies, J.M. Ward, A. Wicht, O. Benson, Appl. Phys. Lett. 102, 041104 (2013).