Experimental investigation of practical unforgeable quantum money

Abstract

Wiesner's unforgeable quantum money scheme is widely celebrated as the first quantum information application. Based on the nocloning property of quantum mechanics, this scheme allows for the creation of credit cards used in authenticated transactions offering security guarantees impossible to achieve by classical means. However, despite its central role in quantum cryptography, its experimental implementation has remained elusive because of the lack of quantum memories and of practical verification techniques. Here, we experimentally implement a quantum money protocol relying on classical verification that rigorously satisfies the security condition for unforgeability. Our system exploits polarization encoding of weak coherent states of light and operates under conditions that ensure compatibility with state-of-the-art quantum memories. We derive working regimes for our system using a security analysis taking into account all practical imperfections. Our results constitute a major step towards a real-world realization of this milestone protocol.

Semi-device-independent quantum money

“…Furthermore, Selby and Sikora [30] analyzed unforgeable money in the Generalized Probabilistic Theories. We should also point out experimental results in the quantum money field were presented by three groups of Bartkiewicz et al [31], Bozzio et al [32], and Guan et al [33] respectively. Although the theoretical schemes are secure, in the case of real-life, more practical implementation, new vectors of attack could appear.…”

“…It is also worth to notice that, recently, the first experimental implementation of quantum money schemes were performed [31][32][33]. It indicates that real-life implementation of quantum money could potentially be achievable using near-future technologies.…”

Experimentally attacking quantum money schemes based on quantum retrieval games

“…An example of such fundamental limitation is the no-cloning theorem, 1,2 which guaranties security of quantum money. 3,4 In a recent paper, Bozzio et al 5 reported on an implementaion of a QM scheme based on QRGs. 6,7 While this result brings QM closer to practical implementation, here we demonstrate that QRG-based QM schemes are still vulnerable to a new kind of attack (for some typical attacks see Ref.…”

“…For the purpose of our research we have experimentally recreated the original scheme of Ref. [ 5]. Its working principle can be described as follows: the bank encodes QM (as a quantum token) using a secret sequence of qubit pairs chosen from the list of eight options: (1) where |0 , |1 are logical qubit states, and |± = 1 √ 2 (|0 ± |1 ) stand for their superpositions.…”

Semi-device-independent quantum money with coherent states

“…An alternative protocol with verification using classical communication was first proposed in [7] and extended to practical, noise-tolerant schemes in [8][9][10].Although quantum key distribution protocols have been widely studied and implemented [11], quantum money has not yet seen the same experimental progress, essentially because of the difficulty in implementing efficient quantum storage devices [12]. However, the experimental interest in quantum money has grown recently, with demonstration of forgery of quantum banknotes [13] and implementation of weak coherent state-based quantum credit card schemes, secure in a trusted terminal scenario [14,15], in the prospect of near-future implementations with a quantum memory. These require new security proofs tackling the optimal cloning of coherent states, differing from qubit-based quantum money and also quantum key distribution proofs.In quantum cryptography, semi-device-independent frameworks have been developed in order to limit the needed assumptions to ensure security.…”