Large-amplitude squeezed cat states and high-quality Gottesman-Kitaev-Preskill (GKP) are essential for effective quantum error correction, yet their optical preparation has been hindered by challenges such as low success probabilities, small amplitudes, insufficient squeezing. Addressing these limitations, our research introduces scalable schemes the deterministic of large-amplitude from photon-number states. Fock have benefit producing consistent across all measurement outcomes...

Quantum repeaters have been proposed as a way of extending the reach quantum communication. First generation approaches use entanglement swapping to connect entangled links along long distance channel. Recently, there proposals for first continuous variables. In this paper, we present an improved variable repeater scheme using optimal Gaussian swapping. Our uses noiseless linear amplifier distillation. We show that with simplest configuration and under assumption good memories perfect...

We introduce a linear optical technique that can implement ideal quantum teleamplification up to the nth Fock state, where n be any positive integer. Here consists of both teleportation and noiseless amplification (NLA). This simple protocol beam splitter an (n+1) splitter, with ancillary photons detection photons. For given target fidelity, our improves success probability physical resource costs by orders magnitude over current alternative NLA schemes. show how this also used as...

We generalize the concept of optical state truncation and noiseless linear amplification to enable Fock-state expansion an higher order simultaneously amplify it using optics. The resulting generalized quantum scissors are more efficient for than employing multiple in parallel experimentally practical. As a particular example, we focus on third-order scissor device demonstrate advantages terms fidelity with target state, probability success, distillable entanglement, amount non-Gaussianity...

Abstract The field of quantum communications promises the faithful distribution information, entanglement, and absolutely secret keys, however, highest rates these tasks are fundamentally limited by transmission distance between repeaters. ultimate end-to-end communication networks known to be achievable an optimal entanglement distillation protocol followed teleportation. In this work, we give a practical design for achievability. Our is iterative approach, where each purification step...

A noiseless linear amplifier (NLA) performs the highest-quality amplification allowable under rules of quantum physics. Unfortunately, these same conspire against us via no-cloning theorem, which constrains NLA operations to domain probabilistic processes. Nevertheless, they are useful for a wide variety protocols, with numerous proposals assuming access an optimal device that maximum possible success probability. Here we propose first linear-optics protocol asymptotically achieves this...

We consider a continuous-variable (CV) quantum key distribution (QKD) protocol over free-space channels, which is simpler and more robust than typical CV QKD protocols. It uses bright laser, squeezed modulated in the amplitude quadrature, self-homodyne detection. scenario, where line of sight classically monitored to detect active eavesdroppers, so that we can assume passive eavesdropper. Under this assumption, analyze security composable finite-size regime. Proper modulation laser...

Noiseless linear amplification (NLA) is useful for a wide variety of quantum protocols. Here we propose fully scalable amplifier which, asymptotically large sizes, can perform perfect fidelity NLA on any state. Given finite resources, however, it designed to coherent states and their arbitrary superpositions. Our scheme generalization the multiphoton scissor teleamplifier, which implement using coherent-state superposition resource Furthermore, prove our also loss-tolerant relay multiary...

Quantum communications harness quantum phenomena like superposition and entanglement to enhance information transfer between remote nodes. Coherent communications, essential for phase-based internet architecture, require optical coherence among nodes typically involve single-photon interference. Challenges preserving integrating advanced detectors have impeded their deployment in existing telecommunication networks. This study introduces innovative approaches the architecture techniques...

Quantum repeaters are used to overcome the exponential photon loss scaling that quantum states acquire as they transmitted over long distances. While for discrete-variable encodings of information have existed some time, approaches continuous-variable encoding only recently been proposed. In this work, we present a method using repeater protocol distribute and utilize it compare rates entanglement distribution between first-generation continuous- repeaters. Such comparison allows us begin...

One of the main problems in quantum communications is how to achieve high rates at long distances. Quantum repeaters, i.e., untrusted, intermediate relay stations, are necessary overcome repeaterless bound which sets fundamental rate-distance limit communications. In this work, we introduce a continuous-variable protocol overcomes and scales like single-repeater using just one linear-optical device called "quantum scissor", combining entanglement distillation swapping elements previous...

Large-amplitude squeezed cat and high-quality Gottesman-Kitaev-Preskill (GKP) states are powerful resources for quantum error correction. However, previous schemes in optics limited to low success probabilities, small amplitudes, squeezing. We overcome these limitations present scalable the deterministic preparation of large-amplitude using only Gaussian operations photon-number measurements. These can be bred prepare approximate GKP states, showing that correction is technically feasible...

Abstract In typical laser communications classical information is encoded by modulating the amplitude of beam and measured via direct detection. We add a layer security using quantum physics to this standard scheme, applicable free-space channels. consider simultaneous classical-quantum communication scheme where in usual way as fluctuations sub-Poissonian noise-floor. For secret key generation, we continuous-variable distribution protocol (CVQKD) Gaussian ensemble squeezed states Under...

The choice between the Schrödinger and Heisenberg pictures can significantly impact computational resources needed to solve a problem, even though they are equivalent formulations of quantum mechanics. Here, we present method for analysing Bosonic circuits based on picture which allows, under certain conditions, useful factoring evolution into signal noise contributions, similar way what be achieved with classical communication systems. We provide examples suggest that this approach may...

Quantum communication facilitates the secure transmission of information and distribution entanglement, but rates at which these tasks can be achieved are fundamentally constrained by capacities quantum channels. Although repeaters typically enhance mitigating losses noise, a simple entanglement swapping protocol via central node is not effective against Pauli dephasing channel due to additional degradation introduced Bell-state measurements. This highlights importance purifying distributed...

The authors explore the information leakage in a continuous-variable communication protocol quantum key distribution due to asymmetry of protocol. proposed symmetric minimum-leakage heralding asymptotically eliminates pure-loss channel and minimizes noisy channel.

The field of quantum communications promises the faithful distribution information, entanglement, and absolutely secret keys. However, highest rates these tasks are fundamentally limited by transmission distances. Quantum repeaters necessary to overcome repeaterless bound which sets fundamental rate-distance limit any communication protocol. ultimate end-to-end repeater networks known be achievable an optimal entanglement-distillation protocol followed teleportation. In this thesis, we give...

Due to turbulence and tracking errors, free-space optical channels involving mobile transceivers are characterized by a signal's partial loss or complete erasure. This work presents an error correction protocol capable of protecting signal passing through such encoding it with ancillary entangled bipartite state. Beyond its ability offer protection under realistic channel conditions, novel our is encompass both classical quantum information on the encoded signal. We show how, relative...

Quantum repeaters are used to overcome the exponential photon loss scaling that quantum states acquire as they transmitted over long distances. While for discrete variable encodings of information have existed some time, novel approaches continuous encoding only recently been proposed. In this work, we present a method using repeater protocol distribute and utilize it compare rates entanglement distribution between first generation repeaters. Such comparison allows us begin benchmark two...

The field of quantum communications promises the faithful distribution information, entanglement, and absolutely secret keys, however, highest rates these tasks are fundamentally limited by transmission distance between repeaters. ultimate end-to-end communication networks known to be achievable an optimal entanglement distillation protocol followed teleportation. In this work, we give a practical design for achievability. Our is iterative approach, where each purification step operates on...

Noiseless linear amplification (NLA) is useful for a wide variety of quantum protocols. Here we propose fully scalable amplifier which, asymptotically large sizes, can perform perfect fidelity NLA on any state. Given finite resources however, it designed to coherent states and their arbitrary superpositions. Our scheme generalisation the multi-photon scissor teleamplifier, which implement using state superposition resource Furthermore, prove our also loss-tolerant relay multi-ary phase-shift...

A noiseless linear amplifier (NLA) performs the highest quality amplification allowable under rules of quantum physics. Unfortunately, these same conspire against us via no-cloning theorem, which constrains NLA operations to domain probabilistic processes. Nevertheless, they are useful for a wide variety protocols, with numerous proposals assuming access an optimal device maximum possible success probability. Here we propose first optics protocol asymptotically achieves this probability...