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Photonics North (PN)

A SPRINT-Based Single Photon Subtractor for PNS Attacks on QKD

Abdolreza Pasharavesh, Michal Bajcsy

Published May 28, 2024• 0 citations
Publisher

Abstract

We present a photon subtraction scheme designed to deterministically extract single photons from multiphoton states within arbitrary input pulses of light using single-photon Raman interaction (SPRINT) [1]. The proposed system comprises two cascaded Lambda-type atoms with transitions selectively coupled to distinct modes of a single chiral waveguide. Through numerical simulations, we evaluate the device's performance in a potential application involving photon-number-splitting (PNS) attacks against quantum key distribution (QKD).

DOI
10.1109/pn62551.2024.10621772

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Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Mar 8, 2016•0 citations
We present a photon subtraction scheme designed to deterministically extract single photons from multiphoton states within arbitrary input pulses of light using single-photon Raman interaction (SPRINT) [1]. The proposed system comprises two cascaded Lambda-type atoms with transitions selectively coupled to distinct modes of a single chiral waveguide. Through numerical simulations, we evaluate the device's performance in a potential application involving photon-number-splitting (PNS) attacks against quantum key distribution (QKD).
We present a specialized photon subtraction scheme that allows for the deterministic extraction of single photons from multiphoton states while preserving the input single-photon states unaltered. The proposed device integrates two Λ-type emitters with transitions selectively coupled to a single chiral waveguide through single photon Raman interaction (SPRINT). We develop a comprehensive theoretical model for the system using the input-output formalism within the SLH framework and conduct numerical simulations to analyze its interaction with traveling few-photon pulses of coherent light. We use these simulations to predict the scheme's operation and highlight how this two-emitter extension improves the original SPRINT-based deterministic single-photon subtraction when it comes to implementing undetectable photon number splitting attack on a quantum key distribution channel.
Abstract We propose a scheme for deterministic single photon subtraction based on Single Photon Raman Interaction (SPRINT) with a three-level quantum emitter coupled to a chiral waveguide and present an analytical and numerical study of its feasibility. We show that single photon subtraction probability for pulsed input light in a coherent or a Fock state can approach unity in the ideal limit and discuss the potential of various reported quantum emitter-waveguide platforms as candidates for experimental realization of our scheme. The use of chiral slow-light photonic crystal waveguides coupled to Λ -type emitters can perform efficient photon subtraction. While integrating cold atoms to such systems remains technically challenging, solid-state emitters offer a potentially practical path to realize such photon subtraction.
Photon-number splitting (PNS) attack poses a significant threat to the security of quantum key-distribution (QKD) systems that utilize weak coherent states (WCS). While this attack has been extensively explored in theory, its experimental realization remains elusive, raising questions about its practical implementation and impact. This study introduces a novel framework to experimentally demonstrate the PNS attack by leveraging single-photon Raman interaction (SPRINT), a well-developed technological capability. We analytically assess the feasibility and practical implications of this attack. Complementing our recently published analysis of the attack, in this work we calculate the detection statistics for phase-randomized WCS and analyze the purity of the quantum state post-attack. Our analysis reveals that indeed current technologies are sufficient to implement the PNS attack, but the eavesdropper’s information gain deviates from theoretical ideals. Moreover, we show that the attack compromises the integrity of the quantum state, introducing a non-zero quantum bit-error rate (QBER). These findings challenge the conventional assumption of perfect information extraction by the attacker through PNS while underscoring the need for robust QKD protocols, such as the coherent one-way (COW) protocol, which are secure against PNS attacks. Beyond their implications for cryptographic security, the findings also offer new insights into fundamental quantum processes, such as single-photon subtraction and the informational changes caused by photon splitting.
The single-photon Raman interaction has emerged as a promising tool for deterministic photon subtraction, acting as a photon-activated switch in which the first arriving photon renders the system transparent to subsequent photons. Here, we employ the input-output formalism to perform a single-photon transport analysis within a photon subtractor consisting of a three-level quantum emitter coupled to a bimodal cavity-waveguide system. The analysis provides the frequency response of the system and reveals how it is affected by the key physical parameters of the cavity modes, such as coupling strengths and decay rates. We utilize these results to calculate the probability of successful photon subtraction from pulses of different temporal shapes, durations, and carrier frequencies. Subsequent analysis combines the input-output formalism with the quantum trajectory method to numerically verify the analytical findings as well as to assess the impact of photon number of the input pulse on the subtractor's performance. Our findings highlight the single-photon model's capability in predicting the system's response to multiphoton inputs in the pulsed regime as well as its potential utility in the design of efficient single-photon subtractors.
Abstract This work presents a deterministic photon subtraction scheme that selectively extracts photons from an input light stream based on their arrival time sequence. The scheme exploits the temporal entanglement generated during single‐photon Raman interaction in a chiral waveguide coupled to a cascade of Λ‐type atoms. It is demonstrated that this photon subtractor enables the generation of high‐fidelity and modal purity multi‐photon Fock states. Using a variational approach, the modal structure of the output light is identified, based on a non‐orthogonal basis formed through post‐selection of the output pulses. Within an input‐output network framework, numerical simulations are performed to calculate the quantum state of the output light. Additionally, the use of the generated Fock‐state pulses in optical interferometry is investigated, demonstrating their potential for quantum metrology applications at the Heisenberg limit.
We demonstrate a passive scheme for deterministic interactions between a single photon and a single atom. Relying on single-photon Raman interaction (SPRINT), this control-fields free scheme swaps a flying qubit, encoded in the two possible input modes of a photon, with a stationary qubit, encoded in the two ground states of the atom, and can be also harnessed to perform universal quantum gates. Using SPRINT we experimentally demonstrated all-optical switching of single photons by single photons, and deterministic extraction of a single photon from an optical pulse. Applicable to any atom-like Lambda system, SPRINT provides a versatile building block for scalable quantum networks based on completely passive nodes interconnected and activated solely by single photons.