| 1. |
- Cui, Guo Dong, et al.
(författare)
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Interfacing On-Demand Quantum Dot Single Photons with a Resonant Atomic Quantum Memory
- 2023
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Ingår i: Quantum 2.0: Proceedings Optica Quantum 2.0 Conference and Exhibition. - : Optica Publishing Group.
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Konferensbidrag (refereegranskat)abstract
- We demonstrate coherent interactions between quantum dot single photons and a resonant 87Rb ensemble in the experiment and show an open quantum system analysis. These results could help build fast hybrid quantum networks.
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| 2. |
- Gerhardt, Stefan, et al.
(författare)
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Optomechanical tuning of the polarization properties of micropillar cavity systems with embedded quantum dots
- 2020
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Ingår i: Physical Review B. - 2469-9950 .- 2469-9969. ; 101:24
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Tidskriftsartikel (refereegranskat)abstract
- Strain tuning emerged as an appealing tool for tuning of fundamental optical properties of solid-state quantum emitters. In particular, the wavelength and fine structure of quantum dot states can be tuned using hybrid semiconductor-piezoelectric devices. Here, we show how an applied external stress can directly impact the polarization properties of coupled InAs quantum dot-micropillar cavity systems. In our experiment, we find that we can reversibly tune the anisotropic polarization splitting of the fundamental microcavity mode by approximately 60 mu eV. We discuss the origin of this tuning mechanism, which arises from an interplay between elastic deformation and the photoelastic effect in our micropillar. Finally, we exploit this effect to tune the quantum dot polarization optomechanically via the polarization-anisotropic Purcell effect. Our work paves the way for optomechanical and reversible tuning of the polarization and spin properties of light-matter-coupled solid-state systems.
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| 3. |
- Hanschke, Lukas, et al.
(författare)
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Coherent scattering: either sub-natural linewidth or anti-bunched light
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Epitaxial quantum dots have emerged as one of the best single–photon sources, not only for applications in photonic quantum technologies but also for testing fundamental properties of quantum optics. One intriguing observation in this area is the emission of photons with subnatural–linewidth from a two-level system under resonant continuous wave excitation. In particular, an open question is whether these subnatural–linewidth photons exhibit simultaneously single–photon characteristics, i.e. show antibunching as a signature of single-photon emission. Here, we demonstrate that this simultaneous observation of subnatural–linewidth and single photoncharacter is not possible with simple resonant excitation. First, we independently confirm single–photon character and subnatural–linewidth by demonstrating antibunching in a Hanbury Brown and Twiss type setup and using high-resolution spectroscopy, respectively. However, when filtering the coherently scattered photons with filter bandwidths on the order of the homogeneous linewidth of the excited state of the two-level system, the antibunching dip vanishes in the correlation measurement. Our experimental work is consistent with recent theoretical findings, and can be explained by a fundamental model considering higher-order photon correlations.
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| 4. |
- Hanschke, Lukas, et al.
(författare)
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Origin of Antibunching in Resonance Fluorescence
- 2020
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 125:17
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Tidskriftsartikel (refereegranskat)abstract
- Resonance fluorescence has played a major role in quantum optics with predictions and later experimental confirmation of nonclassical features of its emitted light such as antibunching or squeezing. In the Rayleigh regime where most of the light originates from the scattering of photons with subnatural linewidth, antibunching would appear to coexist with sharp spectral lines. Here, we demonstrate that this simultaneous observation of subnatural linewidth and antibunching is not possible with simple resonant excitation. Using an epitaxial quantum dot for the two-level system, we independently confirm the single-photon character and subnatural linewidth by demonstrating antibunching in a Hanbury Brown and Twiss type setup and using high-resolution spectroscopy, respectively. However, when filtering the coherently scattered photons with filter bandwidths on the order of the homogeneous linewidth of the excited state of the two-level system, the antibunching dip vanishes in the correlation measurement. Our observation is explained by antibunching originating from photon-interferences between the coherent scattering and a weak incoherent signal in a skewed squeezed state. This prefigures schemes to achieve simultaneous subnatural linewidth and antibunched emission.
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| 5. |
- Jöns, Klaus D., et al.
(författare)
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Two-photon interference from two blinking quantum emitters
- 2017
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Ingår i: Physical Review B. - : AMER PHYSICAL SOC. - 2469-9950 .- 2469-9969. ; 96:7
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the effect of blinking on the two-photon interference measurement from two independent quantum emitters. We find that blinking significantly alters the statistics in the Hong-Ou-Mandel second-order intensity correlation function g((2))(tau) and the outcome of two-photon interference measurements performed with independent quantum emitters. We theoretically demonstrate that the presence of blinking can be experimentally recognized by a deviation from the g(D)((2))(0) = 0.5 value when distinguishable photons from two emitters impinge on a beam splitter. Our findings explain the significant differences between linear losses and blinking for correlation measurements between independent sources and are experimentally verified using a parametric down-conversion photon-pair source. We show that blinking imposes a mandatory cross-check measurement to correctly estimate the degree of indistinguishability of photons emitted by independent quantum emitters.
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| 6. |
- Lettner, Thomas, et al.
(författare)
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Strain-controlled quantum dot fine-structure for entangled-photon generation at 1550 nm
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Entangled-photon generation at 1550nm in the telecom C-band is of critical importance, since it enables the realization of quantum communication protocols over long distance using deployed telecommunication infrastructure. InAs epitaxial quantum dots have recently enabled on-demand generation of entangled pairs of photons in this wavelength range. However, time-dependent state evolution, caused by the fine-structure splitting, currently limits the fidelity to a specific entangled state. Here, we show suppression of the fine-structure for InAs quantum dots using micromachined piezoelectric actuators and demonstrate generation of highly entangled photons in the telecom C-band. At the lowest fine-structure setting, we obtain a maximum fidelity of (90.0 ± 2.7)% (concurrence of (87.5 ± 3.1)%). The concurrence remains high also for moderate (weak) temporal-filtering, with values close to 80% (50%), corresponding to 30% (80%) of collected photons, respectively. The presented fine-structure control opens the way for the exploitation of entangled photons from quantum dots in fiber-based quantum communication protocols.
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| 7. |
- Lettner, Thomas, et al.
(författare)
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Strain-Controlled Quantum Dot Fine Structure for Entangled Photon Generation at 1550 nm
- 2021
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 21:24, s. 10501-10506
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Tidskriftsartikel (refereegranskat)abstract
- Entangled photon generation at 1550 nm in the telecom C-band is of critical importance as it enables the realization of quantum communication protocols over long distance using deployed telecommunication infrastructure. InAs epitaxial quantum dots have recently enabled on-demand generation of entangled photons in this wavelength range. However, time-dependent state evolution, caused by the fine-structure splitting, currently limits the fidelity to a specific entangled state. Here, we show fine-structure suppression for InAs quantum dots using micromachined piezoelectric actuators and demonstrate generation of highly entangled photons at 1550 nm. At the lowest fine-structure setting, we obtain a maximum fidelity of 90.0 +/- 2.7% (concurrence of 87.5 +/- 3.1%). The concurrence remains high also for moderate (weak) temporal filtering, with values close to 80% (50%), corresponding to 30% (80%) of collected photons, respectively. The presented fine-structure control opens the way for exploiting entangled photons from quantum dots in fiber-based quantum communication protocols.
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| 8. |
- Reindl, Marcus, et al.
(författare)
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All-photonic quantum teleportation using on-demand solid-state quantum emitters
- 2018
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Ingår i: Science Advances. - : AMER ASSOC ADVANCEMENT SCIENCE. - 2375-2548. ; 4:12
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Tidskriftsartikel (refereegranskat)abstract
- All-optical quantum teleportation lies at the heart of quantum communication science and technology. This quantum phenomenon is built up around the nonlocal properties of entangled states of light that, in the perspective of real-life applications, should be encoded on photon pairs generated on demand. Despite recent advances, however, the exploitation of deterministic quantum light sources in push-button quantum teleportation schemes remains a major open challenge. Here, we perform an important step toward this goal and show that photon pairs generated on demand by a GaAs quantum dot can be used to implement a teleportation protocol whose fidelity violates the classical limit (by more than 5 SDs) for arbitrary input states. Moreover, we develop a theoretical framework that matches the experimental observations and that defines the degree of entanglement and indistinguishability needed to overcome the classical limit independently of the input state. Our results emphasize that on-demand solid-state quantum emitters are one of the most promising candidates to realize deterministic quantum teleportation in practical quantum networks.
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| 9. |
- Reindl, Marcus, et al.
(författare)
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Phonon-Assisted Two-Photon Interference from Remote Quantum Emitters
- 2017
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Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 17:7, s. 4090-4095
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Tidskriftsartikel (refereegranskat)abstract
- Photonic quantum technologies are on the verge of finding applications in everyday life with quantum cryptography and quantum simulators on the horizon. Extensive research has been carried out to identify suitable quantum emitters and single epitaxial quantum dots have emerged as near-optimal sources of bright, on demand, highly indistinguishable single photons and entangled photon-pairs. In order to build up quantum networks, it is essential to interface remote quantum emitters. However, this is still an outstanding challenge, as the quantum states of dissimilar "artificial atoms" have to be prepared on-demand with high fidelity and the generated photons have to be made indistinguishable in all possible degrees of freedom. Here, we overcome this major obstacle and show an unprecedented two-photon interference (visibility of 51 +/- 5%) from remote strain-tunable GaAs quantum dots emitting on-demand photon-pairs. We achieve this result by exploiting for the first time the full potential of a novel phonon-assisted two-photon excitation scheme, which allows for the generation of highly indistinguishable (visibility of 71 +/- 9%) entangled photon-pairs (fidelity of 90 +/- 2%), enables push-button biexciton state preparation (fidelity of 80 +/- 2%) and outperforms conventional resonant two-photon excitation schemes in terms of robustness against environmental decoherence. Our results mark an important milestone for the practical realization of quantum repeaters and complex multiphoton entanglement experiments involving dissimilar artificial atoms.
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| 10. |
- Schimpf, Christian, et al.
(författare)
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Hyperfine interaction limits polarization entanglement of photons from semiconductor quantum dots
- 2023
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Ingår i: Physical Review B. - 2469-9950 .- 2469-9969. ; 108:8
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Tidskriftsartikel (refereegranskat)abstract
- Excitons in quantum dots are excellent sources of polarization-entangled photon pairs, but a quantitative understanding of their interaction with the nuclear spin bath is still missing. Here we investigate the role of hyperfine energy shifts using experimentally accessible parameters and derive an upper limit to the achievable entanglement fidelity. Our results are consistent with all available literature, indicate that spin noise is often the dominant process limiting the entanglement in InGaAs quantum dots, and suggest routes to alleviate its effect.
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