Publications by authors named "P Loock"
Article Synopsis
- Quantum computers need to protect information from errors, which can be done by encoding it into a logical state suitable for quantum error correction.
- The Gottesman-Kitaev-Preskill (GKP) qubit is a strong candidate for this purpose due to its multiqubit operations that work well at optical frequencies.
- This research successfully demonstrated a GKP state using propagating light at telecommunication wavelengths, showing promising results in nonclassicality and non-Gaussianity, which are essential for future quantum computing developments.
Bell-state projections serve as a fundamental basis for most quantum communication and computing protocols today. However, with current Bell-state measurement schemes based on linear optics, only two of four Bell states can be identified, which means that the maximum success probability of this vital step cannot exceed 50%. Here, we experimentally demonstrate a scheme that amends the original measurement with additional modes in the form of ancillary photons, which leads to a more complex measurement pattern, and ultimately a higher success probability of 62.
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- - Non-Gaussian states are crucial for advancing optical quantum technologies, and the Optical Quantum State Synthesizer (OQSS) is a promising method for their preparation using Gaussian inputs and linear optics.
- - A major challenge is the complexity of simulating the state preparation on classical computers, making it tough to generate essential non-Gaussian states for quantum processing.
- - The authors propose a backcasting approach to simplify the OQSS design, simulating it layer by layer from the final output back to the beginning, which can also limit the photon detection requirements to a maximum of 2 photons.
We formulate the problem of finding the optimal entanglement swapping scheme in a quantum repeater chain as a Markov decision process and present its solution for different repeaters' sizes. Based on this, we are able to demonstrate that the commonly used "doubling" scheme for performing probabilistic entanglement swapping of probabilistically distributed entangled qubit pairs in quantum repeaters does not always produce the best possible raw rate. Focusing on this figure of merit, without considering additional probabilistic elements for error suppression such as entanglement distillation on higher "nesting levels," our approach reveals that a power-of-two number of segments has no privileged position in quantum repeater theory; the best scheme can be constructed for any number of segments.
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- Optical quantum computation needs carefully created multimode photonic quantum states to function effectively.
- The study shows the successful phase locking of two all-optical quantum memories, which allows for the precise timing of releasing two-mode entangled single-photon states.
- The released states maintain their entanglement and nonclassical properties even with release-time differences of up to 400 nanoseconds, validated through advanced measurement techniques.