Key-rate enhancement using qutrit states for quantum key distribution with askew aligned sources

Abstract

It is known that measurement-device-independent quantum key distribution (MDI-QKD) provides ultimate security from all types of side-channel attack against detectors at the expense of low key generation rate. Here, we propose MDI-QKD using 3-dimensional quantum states and show that the protocol improves the secret key rate under the analysis of mismatched-basis statistics. Specifically, we analyze security of the 3d-MDI-QKD protocol with uncharacterized sources, meaning that the original sources contain unwanted states instead of expected one. We simulate secret key rate of the protocol and identify the regime where the key rate is higher than the protocol with the qubit MDI-QKD.

Enhanced Bell state measurement for efficient measurement-device-independent quantum key distribution using 3-dimensional quantum states

“…Before we introduce the discrimination setup, we describe the physical system we are considering and intro- [31]. The diagram is based on a figure from our previous work [54]. In this setup, the photon injection time to the output port is controlled by three different delay lines and a photonic path switch.…”

“…Since the measurement setup detects only the correlation of the photons, an eavesdropper Eve cannot obtain the information that Alice and Bob share by attacking the measurement setup. It has been proven that QKD with highdimensional quantum states has a higher secret key rate than that of traditional qubit QKD [27][28][29][30], and there are also studies that have shown that MDI-QKD with highdimensional states has some advantages compared with qubit MDI-QKD [54,55]. The procedure for MDI-QKD using qutrit states was introduced in our previous work [54].…”

“…Subsequently, Alice and Bob discard trials in which their encoding bases were different after a basis comparison through a public channel. The remaining data become the sifted key, and Alice and Bob can synchronize their information by performing the appropriate post-processing as described in our previous work [54].…”

“…The remaining data are correlated, so these data can be used as a secret key. Then, the security analysis of the MDI-QKD protocol using entangled qutrit states becomes equivalent to that of the QKD protocol using 3-dimensional maximally entangled states, which has already been studied [28,29,54]. According to the results, the secret key rate per sifted signal of the protocol, r 3 ,can be evaluated as shown in Eq.…”

Efficient High-Dimensional Quantum Key Distribution with Hybrid Encoding

“…It has been also found that the efficiency of key distribution increases with qudits in an ideal situation [ 32 , 33 , 34 , 35 , 36 ]. Various high-dimensional QKD protocols have been proposed such as a generalized version of BB84, a multipartite high-dimensional QKD [ 37 ], and MDI-QKDs using high-dimensional quantum states [ 38 , 39 , 40 ]. Moreover, QKD protocols using qudits have been implemented experimentally in various quantum system, for instance, energy-time eigenstates [ 41 , 42 , 43 , 44 , 45 ] and orbital angular momentum (OAM) mode of a single photon [ 46 , 47 , 48 , 49 , 50 ].…”