74 research outputs found
Generation and sampling of quantum states of light in a silicon chip
Implementing large instances of quantum algorithms requires the processing of
many quantum information carriers in a hardware platform that supports the
integration of different components. While established semiconductor
fabrication processes can integrate many photonic components, the generation
and algorithmic processing of many photons has been a bottleneck in integrated
photonics. Here we report the on-chip generation and processing of quantum
states of light with up to eight photons in quantum sampling algorithms.
Switching between different optical pumping regimes, we implement the
Scattershot, Gaussian and standard boson sampling protocols in the same silicon
chip, which integrates linear and nonlinear photonic circuitry. We use these
results to benchmark a quantum algorithm for calculating molecular vibronic
spectra. Our techniques can be readily scaled for the on-chip implementation of
specialised quantum algorithms with tens of photons, pointing the way to
efficiency advantages over conventional computers
Hong-Ou-Mandel interference between independent III-V on silicon waveguide integrated lasers
The versatility of silicon photonic integrated circuits has led to a
widespread usage of this platform for quantum information based applications,
including Quantum Key Distribution (QKD). However, the integration of simple
high repetition rate photon sources is yet to be achieved. The use of
weak-coherent pulses (WCPs) could represent a viable solution. For example,
Measurement Device Independent QKD (MDI-QKD) envisions the use of WCPs to
distill a secret key immune to detector side channel attacks at large
distances. Thus, the integration of III-V lasers on silicon waveguides is an
interesting prospect for quantum photonics. Here, we report the experimental
observation of Hong-Ou-Mandel interference with 46\pm 2% visibility between
WCPs generated by two independent III-V on silicon waveguide integrated lasers.
This quantum interference effect is at the heart of many applications,
including MDI-QKD. Our work represents a substantial first step towards an
implementation of MDI-QKD fully integrated in silicon, and could be beneficial
for other applications such as standard QKD and novel quantum communication
protocols.Comment: 5 pages, 3 figure
Path-encoded high-dimensional quantum communication over a 2 km multicore fiber
Quantum key distribution (QKD) protocols based on high-dimensional quantum
states have shown the route to increase the key rate generation while
benefiting of enhanced error tolerance, thus overcoming the limitations of
two-dimensional QKD protocols. Nonetheless, the reliable transmission through
fiber links of high-dimensional quantum states remains an open challenge that
must be addressed to boost their application. Here, we demonstrate the reliable
transmission over a 2 km long multicore fiber of path-encoded high-dimensional
quantum states. Leveraging on a phase-locked loop system, a stable
interferometric detection is guaranteed, allowing for low error rates and the
generation of 6.3 Mbit/s of secret key rate.Comment: to appear in npj Quantum Informatio
Study of inter-modal four wave mixing in two few-mode fibres with different phase matching properties
We experimentally study inter-modal four-wave mixing (FWM) in few-mode fibres with different phase matching properties. The possibility of transmitting two spatial modes without intermodal FWM cross-talk in the C-band is presented
Multidimensional quantum entanglement with large-scale integrated optics
The ability to control multidimensional quantum systems is key for the
investigation of fundamental science and for the development of advanced
quantum technologies. Here we demonstrate a multidimensional integrated quantum
photonic platform able to robustly generate, control and analyze
high-dimensional entanglement. We realize a programmable bipartite entangled
system with dimension up to on a large-scale silicon-photonics
quantum circuit. The device integrates more than 550 photonic components on a
single chip, including 16 identical photon-pair sources. We verify the high
precision, generality and controllability of our multidimensional technology,
and further exploit these abilities to demonstrate key quantum applications
experimentally unexplored before, such as quantum randomness expansion and
self-testing on multidimensional states. Our work provides a prominent
experimental platform for the development of multidimensional quantum
technologies.Comment: Science, (2018
Inter-modal Raman amplification of OAM fiber modes
Raman scattering among conventional linearly polarized (LP) modes in single mode optical fibers is generally accepted as a promising way to achieve distributed amplification due to the fact that Raman amplification may provide gain at any wavelength, determined by the used pump wavelength, and excellent noise performance. Here, we show that Raman scattering among orbital angular momentum (OAM) modes in optical fibers have similar properties. We show theoretically that the Raman gain among OAM modes is independent on the topological charge of the OAM modes and that the gain efficiency when the pump and signal are parallel (orthogonally) polarized is similar to the Raman scattering among LP modes in parallel (orthogonal) states of polarization. In addition, we experimentally characterize Raman gain among OAM modes in a fiber supporting multiple OAM modes for both the pump and signal. Finally, we discuss the impact of polarization mode dispersion
- …