Limitations on Quantum Key Repeaters

Abstract

A major application of quantum communication is the distribution of entangled particles for use in quantum key distribution (QKD). Due to noise in the communication line, QKD is in practice limited to a distance of a few hundred kilometres, and can only be extended to longer distances by use of a quantum repeater, a device which performs entanglement distillation and quantum teleportation. The existence of noisy entangled states that are undistillable but nevertheless useful for QKD raises the question of the feasibility of a quantum key repeater, which would work beyond the limits of entanglement distillation, hence possibly tolerating higher noise levels than existing protocols. Here we exhibit fundamental limits on such a device in the form of bounds on the rate at which it may extract secure key. As a consequence, we give examples of states suitable for QKD but unsuitable for the most general quantum key repeater protocol.

11+38 pages, 4 figures, Statements for exact p-bits weakened as non-locking bound on measured relative entropy distance contained an error

References in corpus (8)

• Distillation of secret key and entanglement from quantum states
• Randomizing quantum states: Constructions and applications
• Post-selection technique for quantum channels with applications to quantum cryptography
• Quantum Communication With Zero-Capacity Channels
• Experimental Extraction of Secure Correlations from a Noisy Private State
• Quantum states representing perfectly secure bits are always distillable
• Highly Entangled States With Almost No Secrecy
• Distribution and dynamics of entanglement in high-dimensional quantum systems using convex-roof extended negativity

Cited by in corpus (36)

• The role of quantum information in thermodynamics --- a topical review
• Quantum repeaters: From quantum networks to the quantum internet
• Universal Limitations on Quantum Key Distribution over a Network
• Practical figures of merit and thresholds for entanglement distribution in quantum networks
• Relative Entropy Bounds on Quantum, Private and Repeater Capacities
• Measurement-device-independent quantum key distribution for nonstandalone networks
• Aggregating quantum repeaters for the quantum internet
• Capacities of repeater-assisted quantum communications
• Quantum metrology: Heisenberg limit with bound entanglement
• Fundamental limitation on quantum broadcast networks
• When Do Composed Maps Become Entanglement Breaking?
• Eventually Entanglement Breaking Maps
• Fast and reliable entanglement distribution with quantum repeaters: principles for improving protocols using reinforcement learning
• Multipartite entanglement measures: a review
• Upper bounds on device-independent quantum key distribution
• The positive partial transpose conjecture for n=3
• Private states, quantum data hiding and the swapping of perfect secrecy
• Asymptotics of quantum channels
• Eventually entanglement breaking Markovian dynamics: structure and characteristic times
• On the design and analysis of near-term quantum network protocols using Markov decision processes
• The PPT${}^2$ conjecture holds for all Choi-type maps
• Five open problems in quantum information
• Teleportation simulation of bosonic Gaussian channels: Strong and uniform convergence
• Limitations of semidefinite programs for separable states and entangled games
• The PPT square conjecture holds generically for some classes of independent states
• Bounds on quantum nonlocality via partial transposition
• Every entangled state provides an advantage in classical communication
• Asymptotic Properties for Markovian Dynamics in Quantum Theory and General Probabilistic Theories
• Bipartite Bound Entanglement
• Hybrid quantum network design against unauthorized secret-key generation, and its memory cost
• Secure sequential transmission of quantum information
• Random private quantum states
• Decomposable Pauli diagonal maps and Tensor Squares of Qubit Maps
• Limitations for private randomness repeaters
• A Multiplicative Ergodic Theorem for Bistochastic Ergodic Quantum Processes with Applications to Entanglement
• Teleportation Fidelity of Binary Tree Quantum Repeater Networks