Detecting Energy-Time Entanglement

Barbara M. Terhal

Runai Quan, Huibo Hong, Xiao Xiang +6 more

Abstract Quantum time transfer has emerged as a powerful technique, offering sub-picosecond precision and inherent security through the nonlocal temporal correlation property of energy-time entangled biphoton sources. In this paper, we demonstrate the inherent security advantage of quantum time transfer, and the utilization in detecting potential intercept-resend attacks. By investigating the impact of these attacks on the nonlocality identifier associated with nonlocal dispersion cancellation of energy-time entanglement, we establish a security threshold model for detecting intercept-resend attacks. Experimental verification on a 102 km fiber-optic link confirms that even a malicious delay as small as 25 ps can be identified. This investigation serves as a compelling illustration of secure two-way time transfer, safeguarding against intercept-resend attacks, and showcasing its potential applications in fields reliant on authentic time distribution between remote parties.

Dagmar Bruβ

Filip Sośnicki, Michał Mikołajczyk, Ali Golestani +1 more

We experimentally realize two-photon temporal imaging and dispersive Fourier spectrometry within a single optical setup. We measure the joint temporal and spectral intensities for the characterization of energy-time entangled photon pair.

Christof Bernhard, Bänz Bessire, André Stefanov +1 more

We demonstrate spectral amplitude and phase modulation of time-energy entangled photon pairs by means of a spatial light modulator (SLM) [1]. Coincidences are detected by sum frequency generation in a nonlinear crystal which has been applied in several experiments as an ultrafast coincidence detection method to temporally resolve entangled photons on a timescale of fs [2,3]. By taking into account the properties of the detection crystal, we derive an expression for the up-converted frequency signal in the form of a second-order correlation function G(1)[3]. This detection scheme is in contrast to a perfect coincidence detection described by the fourth-order correlation function G(2). However, in former two photon shaping experiments [1,2] the detected signal was compared to simulations based on G(2). We investigate here under which conditions the G(2)ceases to provide an accurate description of the measurements.

Jan Soubusta, Jan Peřina, Ondřej Haderka +2 more