Anonymous conference key agreement in linear quantum networks

Sharing multi-partite quantum entanglement between parties allows for diverse secure communication tasks to be performed. Among them, conference key agreement (CKA), an extension of key distribution to multiple parties, has received much attention recently. Interestingly, CKA can also be performed in a way that protects the identities of the participating…

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Quantum error correction with higher Gottesman-Kitaev-Preskill codes: Minimal measurements and linear optics

We propose two schemes to obtain Gottesman-Kitaev-Preskill (GKP) error syndromes by means of linear-optical operations, homodyne measurements, and GKP ancillas. This includes showing that for a concatenation of GKP codes with an [n,k,d] stabilizer code only 2n measurements are needed in order to obtain the complete syndrome information, significantly reducing the number of measurements…

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Exact rate analysis for quantum repeaters with imperfect memories and entanglement swapping as soon as possible

We present an exact rate analysis for a secret key that can be shared among two parties employing a linear quantum repeater chain. One of our main motivations is to address the question whether simply placing quantum memories along a quantum communication channel can be beneficial in a realistic setting….

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Optimizing quantum codes with an application to the loss channel with partial erasure information

Quantum error correcting codes (QECCs) are the means of choice whenever quantum systems suffer errors, e.g., due to imperfect devices, environments, or faulty channels. By now, a plethora of families of codes is known, but there is no universal approach to finding new or optimal codes for a certain task…

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Limitations of nearest-neighbour quantum networks

Quantum communication research has in recent years shifted to include multi-partite networks for which questions of quantum network routing naturally emerge. To understand the potential for multi-partite routing, we focus on the most promising architectures for future quantum networks – those connecting nodes close to each other. Nearest-neighbour networks such…

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Communication with Unreliable Entanglement Assistance

Entanglement resources can increase transmission rates substantially. Unfortunately, entanglement is a fragile resource that is quickly degraded by decoherence effects. In order to generate entanglement for optical communication, the transmitter first prepares an entangled photon pair locally, and then transmits one of the photons to the receiver through an optical…

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