Perspectives of microwave quantum key distribution in open-air

Abstract

One of the cornerstones of quantum communication is the unconditionally secure distribution of classical keys between remote parties. This key feature of quantum technology is based on the quantum properties of propagating electromagnetic waves, such as entanglement, or the no-cloning theorem. However, these quantum resources are known to be susceptible to noise and losses, which are omnipresent in open-air communication scenarios. In this work, we theoretically investigate the perspectives of continuous-variable open-air quantum key distribution at microwave frequencies. In particular, we present a model describing the coupling of propagating microwaves with a noisy environment. Using a protocol based on displaced squeezed states, we demonstrate that continuous-variable quantum key distribution with propagating microwaves can be unconditionally secure at room temperature up to distances of around 200 meters. Moreover, we show that microwaves can potentially outperform conventional quantum key distribution at telecom wavelength at imperfect weather conditions.

Propagating Quantum Microwaves: Towards Applications in Communication and Sensing

“…Nevertheless, developments in this front would be extremely useful, as they would enable the use of more recent QKD protocols such as the three-state one-decoy BB84 [112]. CV-QKD should be possible to realize today, as demonstrated by the recent publication [28]. In this article, the authors show that using the protocol from Ref.…”

“…In Ref. [28] a full comparison between telecom and microwave regimes was made, concluding that the latter are more robust against unfavourable wheather conditions. In addition to this, the strong interaction of microwaves with non-linear elements give a higher entanglement rate production than telecom frequencies, which could justify the larger loss factor associated with the lack of highly directive emitters that is possible with telecom lasers.…”

“…Recently, theoretical studies taking into account the recent developments in propagating microwaves have indicated the significant potential brought by quantum microwaves for both short distance quantum communication [118], and long distance in the context of satellite communications [28,119]. Furthermore, QKD comes in two different flavors, DV-and CV-QKD.…”

Millimeter-Waves to Terahertz SISO and MIMO Continuous Variable Quantum Key Distribution

“…Demands for 6G are including, but are not limited to, Terabit per second (Tb/s), mm-precision sensing and positioning, seamless connectivity, and ultrafast wireless communications [7][8][9][10][11]. Moreover, practical implementation of quantum processors and quantum computers operating at low temperatures (cryogenics) [53][54][55], requires massive open air and free space data transfer from and to high-performance classical processors, computers, and communication systems. Therefore, to realise a robust building block for practical quantum information processing attention should be on both security and low-temperature operation.…”

Coplanar Antenna Design for Microwave Entangled Signals Propagating in Open Air

“…Recently, it has gained new life thanks to advances in controllability and scalability of superconducting qubits [1], spurring this technology to the top on the field of quantum computation [2]. The development of quantum microwave technology is then vital not only for quantum computation, but also for secure quantum communication protocols [3,4,5,6,7], distributed quantum computing [8], quantum metrology and quantum sensing [9,10,11], specially with the quantum radar on sight [12,13].…”