670 research outputs found
On-chip topological transport of optical frequency combs in silicon-based valley photonic crystals
The generation and control of optical frequency combs in integrated photonic
systems enables complex, high-controllable, and large-scale devices. In
parallel, harnessing topological physics in multipartite systems has allowed
them with compelling features such as robustness against fabrication
imperfections. Here we experimentally demonstrate on-chip topological transport
for optical frequency combs at telecommunication wavelengths, both in classical
and nonclassical domains. We access both the quantum frequency combs and
dissipative Kerr soliton combs with a micro-resonator. The quantum frequency
comb, that is, a coherent superposition of multiple frequency modes, is proven
to be a frequency-entangled qudit state. We also show that dissipative Kerr
soliton combs are highly coherent and mode-locked due to the collective
coherence or self-organization of solitons. Moreover, the valley kink states
allow both quantum frequency combs and dissipative Kerr soliton combs with
robustness against sharp bends. Our topologically protected optical frequency
combs could enable the inherent robustness in integrated complex photonic
systems.Comment: 20 pages,12 figure
Bright quantum photon sources from a topological Floquet resonance
Entanglement, a fundamental concept in quantum mechanics, plays a crucial
role as a valuable resource in quantum technologies. The practical
implementation of entangled photon sources encounters obstacles arising from
imperfections and defects inherent in physical systems and microchips,
resulting in a loss or degradation of entanglement. The topological photonic
insulators, however, have emerged as promising candidates, demonstrating an
exceptional capability to resist defect-induced scattering, thus enabling the
development of robust entangled sources. Despite their inherent advantages,
building bright and programmable topologically protected entangled sources
remains challenging due to intricate device designs and weak material
nonlinearity. Here we present an advancement in entanglement generation
achieved through a non-magnetic and tunable resonance-based anomalous Floquet
insulator, utilizing an optical spontaneous four-wave mixing process. Our
experiment demonstrates a substantial enhancement in entangled photon pair
generation compared to devices reliant solely on topological edge states and
outperforming trivial photonic devices in spectral resilience. This work marks
a step forward in the pursuit of defect-robust and bright entangled sources
that can open avenues for the exploration of cascaded quantum devices and the
engineering of quantum states. Our result could lead to the development of
resilient quantum sources with potential applications in quantum technologies.Comment: 20 pages, 10 figure
Extracting entangled qubits from Majorana fermions in quantum dot chains through the measurement of parity
We propose a scheme for extracting entangled charge qubits from quantum-dot
chains that support zero-energy edge modes. The edge mode is composed of
Majorana fermions localized at the ends of each chain. The qubit, logically
encoded in double quantum dots, can be manipulated through tunneling and
pairing interactions between them. The detailed form of the entangled state
depends on both the parity measurement (an even or odd number) of the
boundary-site electrons in each chain and the teleportation between the chains.
The parity measurement is realized through the dispersive coupling of
coherent-state microwave photons to the boundary sites, while the teleportation
is performed via Bell measurements. Our scheme illustrates \emph{localizable
entanglement} in a fermionic system, which serves feasibly as a quantum
repeater under realistic experimental conditions, as it allows for finite
temperature effect and is robust against disorders, decoherence and
quasi-particle poisoning.Comment: Accepted by Scientific Report
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