Practical implementation and evaluation of a quantum-key-distribution scheme based on the time-frequency uncertainty

Abstract

We implement a quantum-key-distribution protocol which works in analogy to the BB84 protocol with two discrete states each in frequency and time. Its security relies on the frequency-time uncertainty. We show how the protocol is realized with commercial telecom components and discuss technical constraints of existing equipment. In order to evaluate the performance and the security of the protocol against specific attacks we explore quantitatively a large set of parameters. Based on these studies we suggest how further enhancement of security can be obtained with existing technology

Control and Measurement of Quantum Light Pulses for Quantum Information Science and Technology

“…The ability to precisely measure a quantum optical signal in the conjugate frequency and time domains is an essential technique required for many applications in quantum optics, including characterization of quantum light [ 152–154 ] and quantum communications. [ 13,19–21 ] However, the time‐bandwidth product for light pulses typically leads to challenges in measuring both time and frequency distributions. For example, single photons occupying an ultrashort (≈100 fs) pulse have a broad spectrum (≈10 THz) that can be easily measured with a spectrometer.…”

“…A concrete example of an application that requires an equal number of independent measurement outcomes in conjugate time–frequency bases arises in time–frequency quantum‐key distribution (QKD). [ 13,20 ] Accessing conjugate arrival time and frequency bases requires measurements with compatible time and frequency resolution and as described above. Typically when performing direct measurements in one basis, the required resolution in the conjugate basis is not directly accessible for single‐photon coincident measurements.…”

“…A similar experiment has been realized in ref. [20] with two bins in both time and frequency domains with state‐of‐the‐art components at telecom wavelength.…”

“…[ 7 ] Recently there has been significant interest in utilizing the temporal‐spectral degree of freedom of light that underlies ultrashort optical pulses for quantum information science and technology. [ 4,8–16 ] Quantum applications enabled by information encoded in the temporal mode of photons include linear optics quantum computing, [ 4,16,17 ] boson sampling, [ 18 ] quantum communications [ 13,19–21 ] and quantum sensing. [ 22,23 ] Here we focus on manipulation of one‐ and two‐photon states of light and applications enabled by this control.…”

Quantum measurements of signals from the Alphasat TDP1 laser communication terminal

“…Existing fiber infrastructure is not suitable for this purpose since classical telecom repeaters cannot relay quantum states [2]. Therefore, optical satellite-to-ground communication [17][18][19][20][21][22] lends itself to bridge intercontinental distances for quantum communication [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]. …”