“…|g (1) (τ )| g (1) (0) , (17) demonstrating that once the interferometer imperfections are accounted for by the (1 − ϵ) term, v(τ ) corresponds to the absolute value of the normalised coarse grained first-order correlation function.…”
Section: Experimental Methodsmentioning
confidence: 99%
“…Indistinguishable photons from such sources have facilitated important quantum technology demonstrations, including linear optical quantum computing [12,13] and entanglement swapping for quantum communications and networking [14,15]. Furthermore, similar methods can be extended to produce more complex resource states for optical quantum technologies, such as recent demonstrations of entangled graph states [16][17][18] where high fidelities are enabled by indistinguishable photons. Beyond QDs, the cavity-emitter concept has also been applied to realise photon sources using quantum emitters in other solid-state hosts such as diamond [19], silicon [20] and 2D materials [21].…”
Solid-state emitters such as epitaxial quantum dots have emerged as a leading platform for efficient, on-demand sources of indistinguishable photons, a key resource for many optical quantum technologies. To maximise performance, these sources normally operate at liquid helium temperatures (~4 K), introducing significant size, weight and power requirements that can be impractical for proposed applications. Here we experimentally resolve the two distinct temperature-dependent phonon interactions that degrade indistinguishability, allowing us to demonstrate that coupling to a photonic nanocavity can greatly improve photon coherence at elevated temperatures compatible with compact cryocoolers. We derive a polaron model that fully captures the temperature-dependent influence of phonons observed in our experiments, providing predictive power to further increase the indistinguishability and operating temperature of future devices through optimised cavity parameters.
“…|g (1) (τ )| g (1) (0) , (17) demonstrating that once the interferometer imperfections are accounted for by the (1 − ϵ) term, v(τ ) corresponds to the absolute value of the normalised coarse grained first-order correlation function.…”
Section: Experimental Methodsmentioning
confidence: 99%
“…Indistinguishable photons from such sources have facilitated important quantum technology demonstrations, including linear optical quantum computing [12,13] and entanglement swapping for quantum communications and networking [14,15]. Furthermore, similar methods can be extended to produce more complex resource states for optical quantum technologies, such as recent demonstrations of entangled graph states [16][17][18] where high fidelities are enabled by indistinguishable photons. Beyond QDs, the cavity-emitter concept has also been applied to realise photon sources using quantum emitters in other solid-state hosts such as diamond [19], silicon [20] and 2D materials [21].…”
Solid-state emitters such as epitaxial quantum dots have emerged as a leading platform for efficient, on-demand sources of indistinguishable photons, a key resource for many optical quantum technologies. To maximise performance, these sources normally operate at liquid helium temperatures (~4 K), introducing significant size, weight and power requirements that can be impractical for proposed applications. Here we experimentally resolve the two distinct temperature-dependent phonon interactions that degrade indistinguishability, allowing us to demonstrate that coupling to a photonic nanocavity can greatly improve photon coherence at elevated temperatures compatible with compact cryocoolers. We derive a polaron model that fully captures the temperature-dependent influence of phonons observed in our experiments, providing predictive power to further increase the indistinguishability and operating temperature of future devices through optimised cavity parameters.
“…An alternative and, in principle, deterministic approach using a sequence of single photons emitted from a single memory spin was recognized early on 5 , 7 , 33 but could not be realized owing to technological shortcomings. The strategy was implemented only recently but with remarkable progress 9 – 15 that finally led to an outperformance of SPDC systems in the achievable number of entangled photons 16 . Fig.…”
Entanglement has evolved from an enigmatic concept of quantum physics to a key ingredient of quantum technology. It explains correlations between measurement outcomes that contradict classical physics and has been widely explored with small sets of individual qubits. Multi-partite entangled states build up in gate-based quantum-computing protocols and—from a broader perspective—were proposed as the main resource for measurement-based quantum-information processing1,2. The latter requires the ex-ante generation of a multi-qubit entangled state described by a graph3–6. Small graph states such as Bell or linear cluster states have been produced with photons7–16, but the proposed quantum-computing and quantum-networking applications require fusion of such states into larger and more powerful states in a programmable fashion17–21. Here we achieve this goal by using an optical resonator22 containing two individually addressable atoms23,24. Ring25 and tree26 graph states with up to eight qubits, with the names reflecting the entanglement topology, are efficiently fused from the photonic states emitted by the individual atoms. The fusion process itself uses a cavity-assisted gate between the two atoms. Our technique is, in principle, scalable to even larger numbers of qubits and is the decisive step towards, for instance, a memory-less quantum repeater in a future quantum internet27–29.
“…Typical SPS g (2) (τ) for (f) a two-level and three-level systems with CW excitation and (g) a two-level system with pulsed excitation. defect coherent control could open the opportunity to explore spin-qubits in this material and spin-photon entanglement distribution 22,23 if the spin coherence will be determined to be long enough. Finally, the nanophotonic structures in GaN, combined with its nonlinear optical properties, could provide devices for frequency conversion, 24,25 novel quantum light sources based on spontaneous parametric down-conversion in a chip, 26 and SPS enhancement via Purcell's effect in monolithic nanostructures.…”
Section: Introductionmentioning
confidence: 99%
“…Both SPSs and optical spin-read-out systems are building blocks for quantum technologies such as quantum communication and computation (SPSs and spin-qubits); , the spin-optical read-out can be used for quantum sensing and bright single-photon emission can be used for quantum radiometry . The availability of RE doping in GaN opens the opportunity to have in the same material quantum memories, while spin defect coherent control could open the opportunity to explore spin-qubits in this material and spin-photon entanglement distribution , if the spin coherence will be determined to be long enough. Finally, the nanophotonic structures in GaN, combined with its nonlinear optical properties, could provide devices for frequency conversion, , novel quantum light sources based on spontaneous parametric down-conversion in a chip, and SPS enhancement via Purcell’s effect in monolithic nanostructures …”
Gallium nitride (GaN) is an advanced semiconductor primarily
known
for its current applications in lasers and high-power electronics.
With the availability of various growth techniques for both thin films
and nanomaterials, which result in high-purity materials, and its
exceptional electrical and optical properties, GaN stands in a unique
position for potential expansion into other fields, particularly in
the realm of quantum technologies. In recent years, there have been
notable advancements in GaN quantum dots, nanowires, and more recently
color centers, revealing promising optical and spin quantum properties
that could pave the way for further developments in the future. This
review offers a comprehensive review of recent studies focused on
the quantum properties of GaN materials, particularly in terms of
single-photon emission and the characteristics of color centers. While
GaN is still in the early stages of assessment compared to other emerging
quantum materials, we present a perspective on its unexplored potential,
which holds the promise of unlocking new opportunities for the advancement
of quantum technologies.
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