Quantum information and communication with high-dimensional encoding

Project overview & objectives

High-dimensional (HD) photonic quantum information (QI) promises considerable advantages compared to the 2D qubit paradigm, from increased quantum communication rates to increased robustness for entanglement distribution. QuICHE aims to unlock the potential of HD QI by encoding information in the spectral-temporal (ST) degrees of freedom of light. ST control of quantum states of light enables multiplexing of QI in a single spatial mode, ideally suited for guided-wave communications and integrated devices. QI encoding in HD states has been recognized as a promising way towards enhanced QI processing, communication, and sensing. In QuICHE matched experimental tools and theoretical architectures for manipulating and characterizing such states will be developed, and their use will be demonstrated in various applications.

  • HD encoding and multiplexing schemes in time and frequency for quantum protocols with single systems (QKD, channel capacities, dimension witnesses)
  • HD schemes for quantum protocols with composite systems (Superdense coding, Bell violation, entanglement witness, conditional non-classicality)
  • Interfaces between ST encodings using quantum temporal imaging and memories (Hybrid encoding networks, low-loss encoding conversion, conversion of time scales)


Key concepts

Quantum temporal imaging

Theory of noiseless compression and stretching of temporal waveforms carrying high-dimensional quantum encoding.

Theory of quantum multiplexing of temporal modes for producing high dimensional entangled states.

Time-frequency bins

  • QI encoding in the bases of time and frequency bins naturally compatible with direct single photon detection
  • Bandwidth-mathced spectrally and temporally resolved single-photon measurements
  • General measurements schemes in time-frequency bin basis

Concepts for high-dimensional encodings

  • Development of efficient methods for:
    • entanglement detection,
    • Bell-inequality violation,
    • randomness expansion
  • Theoretical analysis tailored for experiments.
  • Explicit security analysis for HD QKD (with practical imitations).
  • Towards Quantum Internet:
    • HD-encoded quantum networks,
    • efficient network coding strategies,
    • multipartite HD-QKD.

Pulse modes

We will develop a toolset for HD QI based on pulse modes, which comprises of devices and methods for the generation, manipulation, detection, and verification of user-defined pulse-mode structures.

Applications with high-dimensional encodings

  • High-dimensional QKD schemes based on pulse modes surpass the secret key rates of low-dimensional schemes
  • Realisation of devices for quantum temporal imaging and the demonstration of survival of quantum properties
  • Implementation of flexible interfaces between pulse modes and time-frequency bins for use in hybrid encoding networks

Consortium meeting

The first in-person QuICHE Consortium meeting took place in Düsseldorf on 22-23 March 2022. Representatives of all the consortium members joined the meeting to report their progress and discuss further research. Cheers to the Düsseldorf team for organizing a great meeting!