Hadamard quantum broadcast channels

Wang, Qingle; Das, Siddhartha; Wilde, Mark M.

doi:10.1007/s11128-017-1697-5

Cited by 25 publications

(16 citation statements)

References 49 publications

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“…We then prove that this rate region is optimal if the multi-mode version of Theorem 1 is true. For the case in which the amplifier channel is quantum-limited, the capacity region is single-letter [30] and therefore Theorem 1 implies the broadcast capacity region for the quantum-limited amplifier channel.…”

Section: Quantum Broadcast Amplifier Channelmentioning

confidence: 96%

“…Now let us consider the quantum-limited amplifier channel. Since the broadcast capacity region for Hadamard channels is single-letter [30], by setting n = 1 and N B = 0 in the above proof, we establish the following:…”

Section: B Outer Bound For the Capacity Regionmentioning

confidence: 97%

“…However, a quantum-limited amplifier channel, the complementary channel of which is entanglement-breaking, is a Hadamard channel [26,27]. It is known that the capacity regions of both the information trade-off and broadcast problems are single-letter for Hadamard channels [20,[28][29][30].…”

Section: Minimum Output-entropy Theoremmentioning

confidence: 99%

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Capacities of quantum amplifier channels

Wilde

2017

Phys. Rev. A

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Quantum amplifier channels are at the core of several physical processes. Not only do they model the optical process of spontaneous parametric down-conversion, but the transformation corresponding to an amplifier channel also describes the physics of the dynamical Casimir effect in superconducting circuits, the Unruh effect, and Hawking radiation. Here we study the communication capabilities of quantum amplifier channels. Invoking a recently established minimum output-entropy theorem for single-mode phase-insensitive Gaussian channels, we determine capacities of quantum-limited amplifier channels in three different scenarios. First, we establish the capacities of quantum-limited amplifier channels for one of the most general communication tasks, characterized by the trade-off between classical communication, quantum communication, and entanglement generation or consumption. Second, we establish capacities of quantum-limited amplifier channels for the trade-off between public classical communication, private classical communication, and secret key generation. Third, we determine the capacity region for a broadcast channel induced by the quantum-limited amplifier channel, and we also show that a fully quantum strategy outperforms those achieved by classical coherent detection strategies. In all three scenarios, we find that the capacities significantly outperform communication rates achieved with a naive time-sharing strategy.

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Section: Quantum Broadcast Amplifier Channelmentioning

confidence: 96%

Section: B Outer Bound For the Capacity Regionmentioning

confidence: 97%

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Capacities of quantum amplifier channels

Wilde

2017

Phys. Rev. A

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“…The weight of the edge is then defined to be p ln -( ). Boundary conditions are handled according to the techniques of [102].…”

Section: A2 Swap-lrmentioning

confidence: 99%

Handling leakage with subsystem codes

2019

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Leakage is a particularly damaging error that occurs when a qubit state falls out of its two-level computational subspace. Compared to independent depolarizing noise, leaked qubits may produce many more configurations of harmful correlated errors during error-correction. In this work, we investigate different local codes in the low-error regime of a leakage gate error model. When restricting to bare-ancilla extraction, we observe that subsystem codes are good candidates for handling leakage, as their locality can limit damaging correlated errors. As a case study, we compare subspace surface codes to the subsystem surface codes introduced by Bravyi et al. In contrast to depolarizing noise, subsystem surface codes outperform same-distance subspace surface codes below error rates as high as 7.5×10 −4 while offering better per-qubit distance protection. Furthermore, we show that at low to intermediate distances, Bacon-Shor codes offer better per-qubit error protection against leakage in an ion-trap motivated error model below error rates as high as 1.2×10 −3 . For restricted leakage models, this advantage can be extended to higher distances by relaxing to unverified two-qubit cat state extraction in the surface code. These results highlight an intrinsic benefit of subsystem code locality to error-corrective performance.

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“…Secrecy in the form of quantum state masking was recently considered in [63]. Quantum broadcast channels were studied in various settings as well, e.g., [64][65][66][67][68][69][70][71][72][73][74]. Yard et al [64] derived the superposition inner bound and determined the capacity region for the degraded classical-quantum broadcast channel.…”

mentioning

confidence: 99%

Key Assistance, Key Agreement, and Layered Secrecy for Bosonic Broadcast Channels

Pereg¹,

Ferrara²,

Bloch³

2021

Preprint

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Secret-sharing building blocks based on quantum broadcast communication are studied. The confidential capacity region of the pure-loss bosonic broadcast channel is determined, both with and without key assistance, and an achievable region is established for the lossy bosonic broadcast channel. If the main receiver has a transmissivity of η < 1 2 , then confidentiality solely relies on the key-assisted encryption of the one-time pad. We also address conference key agreement for the distillation of two keys, a public key and a secret key. A regularized formula is derived for the key-agreement capacity region in finite dimensions. In the bosonic case, the key-agreement region is included within the capacity region of the corresponding broadcast channel with confidential messages. We then consider a network with layered secrecy, where three users with different security ranks communicate over the same broadcast network. We derive an achievable layered-secrecy region for a pure-loss bosonic channel that is formed by the concatenation of two beam splitters.

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Hadamard quantum broadcast channels

Cited by 25 publications

References 49 publications

Capacities of quantum amplifier channels

Capacities of quantum amplifier channels

Handling leakage with subsystem codes

Key Assistance, Key Agreement, and Layered Secrecy for Bosonic Broadcast Channels

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