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Inverse-designed diamond photonics
Diamond hosts optically active color centers with great promise in quantum computation, networking, and sensing. Realization of such applications is contingent upon the integration of color centers into photonic circuits. However, current diamond quantum optics experiments are restricted to single devices and few quantum emitters because fabrication constraints limit device functionalities, thus precluding color center integrated photonic circuits. In this work, we utilize inverse design methods to overcome constraints of cutting-edge diamond nanofabrication methods and fabricate compact and robust diamond devices with unique specifications. Our design method leverages advanced optimization techniques to search the full parameter space for fabricable device designs. We experimentally demonstrate inverse-designed photonic free-space interfaces as well as their scalable integration with two vastly different devices: classical photonic crystal cavities and inverse-designed waveguide-splitters. The multi-device integration capability and performance of our inverse-designed diamond platform represents a critical advancement toward integrated diamond quantum optical circuits
Deterministic integration of quantum dots into on-chip multi-mode interference beamsplitters using in-situ electron beam lithography
The development of multi-node quantum optical circuits has attracted great
attention in recent years. In particular, interfacing quantum-light sources,
gates and detectors on a single chip is highly desirable for the realization of
large networks. In this context, fabrication techniques that enable the
deterministic integration of pre-selected quantum-light emitters into
nanophotonic elements play a key role when moving forward to circuits
containing multiple emitters. Here, we present the deterministic integration of
an InAs quantum dot into a 50/50 multi-mode interference beamsplitter via
in-situ electron beam lithography. We demonstrate the combined emitter-gate
interface functionality by measuring triggered single-photon emission on-chip
with . Due to its high patterning resolution as well
as spectral and spatial control, in-situ electron beam lithography allows for
integration of pre-selected quantum emitters into complex photonic systems.
Being a scalable single-step approach, it paves the way towards multi-node,
fully integrated quantum photonic chips.Comment: 20 pages, 5 figure
Optimal photonic indistinguishability tests in multimode networks
Particle indistinguishability is at the heart of quantum statistics that
regulates fundamental phenomena such as the electronic band structure of
solids, Bose-Einstein condensation and superconductivity. Moreover, it is
necessary in practical applications such as linear optical quantum computation
and simulation, in particular for Boson Sampling devices. It is thus crucial to
develop tools to certify genuine multiphoton interference between multiple
sources. Here we show that so-called Sylvester interferometers are near-optimal
for the task of discriminating the behaviors of distinguishable and
indistinguishable photons. We report the first implementations of integrated
Sylvester interferometers with 4 and 8 modes with an efficient, scalable and
reliable 3D-architecture. We perform two-photon interference experiments
capable of identifying indistinguishable photon behaviour with a Bayesian
approach using very small data sets. Furthermore, we employ experimentally this
new device for the assessment of scattershot Boson Sampling. These results open
the way to the application of Sylvester interferometers for the optimal
assessment of multiphoton interference experiments.Comment: 9+10 pages, 6+6 figures, added supplementary material, completed and
updated bibliograph
Nanomechanical single-photon routing
The merger between integrated photonics and quantum optics promises new
opportunities within photonic quantum technology with the very significant
progress on excellent photon-emitter interfaces and advanced optical circuits.
A key missing functionality is rapid circuitry reconfigurability that
ultimately does not introduce loss or emitter decoherence, and operating at a
speed matching the photon generation and quantum memory storage time of the
on-chip quantum emitter. This ambitious goal requires entirely new active
quantum-photonic devices by extending the traditional approaches to
reconfigurability. Here, by merging nano-optomechanics and deterministic
photon-emitter interfaces we demonstrate on-chip single-photon routing with low
loss, small device footprint, and an intrinsic time response approaching the
spin coherence time of solid-state quantum emitters. The device is an essential
building block for constructing advanced quantum photonic architectures
on-chip, towards, e.g., coherent multi-photon sources, deterministic
photon-photon quantum gates, quantum repeater nodes, or scalable quantum
networks.Comment: 7 pages, 3 figures, supplementary informatio
Dynamically controlling the emission of single excitons in photonic crystal cavities
Single excitons in semiconductor microcavities represent a solid-state and
scalable platform for cavity quantum electrodynamics (c-QED), potentially
enabling an interface between flying (photon) and static (exciton) quantum bits
in future quantum networks. While both single-photon emission and the strong
coupling regime have been demonstrated, further progress has been hampered by
the inability to control the coherent evolution of the c-QED system in real
time, as needed to produce and harness charge-photon entanglement. Here, using
the ultrafast electrical tuning of the exciton energy in a photonic crystal
(PhC) diode, we demonstrate the dynamic control of the coupling of a single
exciton to a PhC cavity mode on a sub-ns timescale, faster than the natural
lifetime of the exciton, for the first time. This opens the way to the control
of single-photon waveforms, as needed for quantum interfaces, and to the
real-time control of solid-state c-QED systems.Comment: 8 pages, 4 figure
System-performance analysis of optimized gain-switched pulse source employed in 40-and 80-Gb/s OTDM systems
The development of ultrashort optical pulse sources, exhibiting excellent temporal and spectral profiles, will play a crucial role in the performance of future optical time division multiplexed (OTDM) systems. In this paper, we demonstrate the difference in performance in 40- and 80-Gb/s OTDM systems between optical pulse sources based on a gain-switched laser whose pulses are compressed by a nonlinearly and linearly chirped fiber Bragg grating. The results achieved show that nonlinear chirp in the wings of the pulse leads to temporal pedestals formed on either side of the pulse when using the linearly chirped grating, whereas with the nonlinearly chirped grating, pedestals are essentially eliminated. In an OTDM system, these pedestals cause coherent interaction between neighboring channels, resulting in intensity fluctuations that lead to a power penalty of 1.5 dB (40 Gb/s) and 3.5 dB (80 Gb/s) in comparison to the case where the nonlinearly chirped grating is used. Simulations carried out with the aid of Virtual Photonics Inc. verify the results achieved
Supervised Quantum Learning without Measurements
We propose a quantum machine learning algorithm for efficiently solving a
class of problems encoded in quantum controlled unitary operations. The central
physical mechanism of the protocol is the iteration of a quantum time-delayed
equation that introduces feedback in the dynamics and eliminates the necessity
of intermediate measurements. The performance of the quantum algorithm is
analyzed by comparing the results obtained in numerical simulations with the
outcome of classical machine learning methods for the same problem. The use of
time-delayed equations enhances the toolbox of the field of quantum machine
learning, which may enable unprecedented applications in quantum technologies
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