76 research outputs found
Tapering of fs Laser-written Waveguides
The vast development of integrated quantum photonic technology enables the
implementation of compact and stable interferometric networks. In particular
laser-written waveguide structures allow for complex 3D-circuits and
polarization-encoded qubit manipulation. However, the main limitation for the
scale-up of integrated quantum devices is the single-photon loss due to
mode-profile mismatch when coupling to standard fibers or other optical
platforms. Here we demonstrate tapered waveguide structures, realized by an
adapted femtosecond laser writing technique. We show that coupling to standard
single-mode fibers can be enhanced up to 77% while keeping the fabrication
effort negligible. This improvement provides an important step for processing
multi-photon states on chip
Bloch Oscillations of Einstein-Podolsky-Rosen States
Bloch Oscillations (BOs) of quantum particles manifest themselves as periodic
spreading and re-localization of the associated wave functions when traversing
lattice potentials subject to external gradient forces. Albeit BOs are deeply
rooted into the very foundations of quantum mechanics, all experimental
observations of this phenomenon so far have only contemplated dynamics of one
or two particles initially prepared in separable local states, which is well
described by classical wave physics. Evidently, a more general description of
genuinely quantum BOs will be achieved upon excitation of a Bloch-oscillator
lattice system by nonlocal states, that is, containing correlations in
contradiction with local realism. Here we report the first experimental
observation of BOs of two-particle Einstein-Podolsky-Rosen states (EPR), whose
associated N-particle wave functions are nonlocal by nature. The time evolution
of two-photon EPR states in Bloch-oscillators, whether symmetric, antisymmetric
or partially symmetric, reveals unexpected transitions from particle
antibunching to bunching. Consequently, the initial state can be tailored to
produce spatial correlations akin to bosons, fermions or anyons. These results
pave the way for a wider class of photonic quantum simulators.Comment: 21 pages, 6 figure
Photon Pair Source based on PPLN-Waveguides for Entangled Two-Photon Absorption
Fluorescence excitation by absorption of entangled photon pairs can reduce
disadvantages of classical imaging techniques, like higher signal levels at low
excitation power with simultaneous reduction of phototoxicity. However, current
entangled photon pair sources are unreliable for fluorescence detection. To
overcome this issue, ultra bright entangled photon pair source are desirable to
based on nonlinear waveguides are promising candidates to enable fluorescence
excitation by entangled photons. In this paper, a source consisting of a
periodically poled lithium niobate waveguide was developed and its key
characteristics analysed. To demonstrate its suitability as key component for
imaging experiments, the entangled two-photon absorption behavior of CdSe/ZnS
quantum dot solutions was experimentally investigated.Comment: 8 pages, 5 figure
Experimental quantum imaging distillation with undetected light
Imaging based on the induced coherence effect makes use of photon pairs to
obtain information of an object without detecting the light that probes it.
While one photon illuminates the object, only its partner is detected, so no
measurement of coincidence events are needed. The sought-after object's
information is revealed observing a certain interference pattern on the
detected photon. Here we demonstrate experimentally that this imaging technique
can be made resilient to noise. We introduce an imaging distillation approach
based on the interferometric modulation of the signal of interest. We show that
our scheme can generate a high-quality image of an object even against noise
levels up to 250 times the actual signal of interest. We also include a
detailed theoretical explanation of our findings.Comment: 18 pages, 6 figures, and 1 table + 11 pages, 3 figures, and 1 tabl
Endurance of quantum coherence due to particle indistinguishability in noisy quantum networks
Quantum coherence, the physical property underlying fundamental phenomena
such as multi-particle interference and entanglement, has emerged as a valuable
resource upon which modern technologies are founded. In general, the most
prominent adversary of quantum coherence is noise arising from the interaction
of the associated dynamical system with its environment. Under certain
conditions, however, the existence of noise may drive quantum and classical
systems to endure intriguing nontrivial effects. In this vein, here we
demonstrate, both theoretically and experimentally, that when two
indistinguishable non-interacting particles co-propagate through quantum
networks affected by non-dissipative noise, the system always evolves into a
steady state in which coherences accounting for particle indistinguishabilty
perpetually prevail. Furthermore, we show that the same steady state with
surviving quantum coherences is reached even when the initial state exhibits
classical correlations.Comment: arXiv admin note: substantial text overlap with arXiv:1709.0433
Perspectives for applications of quantum imaging
Quantum imaging is a multifaceted field of research that promises highly efficient imaging in extreme spectral ranges as well as ultralow‐light microscopy. Since the first proof‐of‐concept experiments over 30 years ago, the field has evolved from highly fascinating academic research to the verge of demonstrating practical technological enhancements in imaging and microscopy. Here, the aim is to give researchers from outside the quantum optical community, in particular those applying imaging technology, an overview of several promising quantum imaging approaches and evaluate both the quantum benefit and the prospects for practical usage in the near future. Several use case scenarios are discussed and a careful analysis of related technology requirements and necessary developments toward practical and commercial application is provided
Enhanced protein synthesis and secretion using a rational signal-peptide library approach as a tailored tool
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