Aleksandr Grigorev

Emission and Absorption of Microwave Photons in Orthogonal Temporal Modes across a 30-Meter Two-Node Network

  1. Alonso Hernández-Antón,
  2. Josua D. Schär,
  3. Aleksandr Grigorev,
  4. Guillermo F. Peñas,
  5. Ricardo Puebla,
  6. Juan José García-Ripoll,
  7. Jean-Claude Besse,
  8. Andreas Wallraff,
  9. and Anatoly Kulikov
The tunable interaction between stationary quantum bits and propagating modes of light allows for the encoding of quantum information in the state of itinerant photons. This ability
fulfills a central requirement for quantum networking, enabling quantum state transfer between distant quantum devices. Conventionally, a symmetric envelope of the photon wavepacket is used for such purposes. Yet, the use of alternative \textit{temporal modes} enables multiple applications in waveguide quantum electrodynamics that remain unexplored experimentally. Here, we use superconducting quantum circuits to generate individual itinerant microwave photons shaped in three mutually orthogonal temporal modes. We transfer the created photons across a 30-m cryogenic link, showing that the orthogonality allows us to decide at the receiver which mode to absorb, reflecting the other two with a selectivity ratio of 40. This experimental capability extends the microwave-frequency quantum communication toolbox, enabling a new photonic degree of freedom.
arxiv pdf

Deterministic generation of a 20-qubit two-dimensional photonic cluster state

  1. James O'Sullivan,
  2. Kevin Reuer,
  3. Aleksandr Grigorev,
  4. Xi Dai,
  5. Alonso Hernández-Antón,
  6. Manuel H. Muñoz-Arias,
  7. Christoph Hellings,
  8. Alexander Flasby,
  9. Dante Colao Zanuz,
  10. Jean-Claude Besse,
  11. Alexandre Blais,
  12. Daniel Malz,
  13. Christopher Eichler,
  14. and Andreas Wallraff
Multidimensional cluster states are a key resource for robust quantum communication, measurement-based quantum computing and quantum metrology. Here, we present a device capable of
emitting large-scale entangled microwave photonic states in a two dimensional ladder structure. The device consists of a pair of coupled superconducting transmon qubits which are each tuneably coupled to a common output waveguide. This architecture permits entanglement between each transmon and a deterministically emitted photonic qubit. By interleaving two-qubit gates with controlled photon emission, we generate 2 x n grids of time- and frequency-multiplexed cluster states of itinerant microwave photons. We measure a signature of localizable entanglement across up to 20 photonic qubits. We expect the device architecture to be capable of generating a wide range of other tensor network states such as tree graph states, repeater states or the ground state of the toric code, and to be readily scalable to generate larger and higher dimensional states.
arxiv pdf