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Bosonic coding: introduction and use cases

Victor V. Albert

TL;DR

The paper surveys bosonic coding as a framework for robust quantum information processing in continuous-variable CV systems, classifying codes into bosonic stabilizer codes and bosonic Fock-state codes. It details representative constructions such as GKP, GKP-stabilizer, cat, binomial, and number-phase codes, and discusses how infinite dimensionality enables error correction beyond DV limits, including continuous transversal gates and bias-preserving dynamics. It analyzes noise models—loss, dephasing, and displacement—and maps code performance to these channels, highlighting hardware efficiency gains and decoding strategies that leverage analog information. The work emphasizes practical implications for quantum memories and communications, including the capacity for Gaussian-displacement channels and the potential for integrating bosonic and DV approaches to achieve scalable fault-tolerant quantum computation with non-Gaussian resources like GKP states. It also points to open questions, such as thresholds for GKP-based schemes and the broader role of bosonic codes in quantum simulation and topological modeling.

Abstract

Bosonic or continuous-variable coding is a field concerned with robust quantum information processing and communication with electromagnetic signals or mechanical modes. I review bosonic quantum memories, characterizing them as either bosonic stabilizer or bosonic Fock-state codes. I then enumerate various applications of bosonic encodings, four of which circumvent no-go theorems due to the intrinsic infinite-dimensionality of bosonic systems.

Bosonic coding: introduction and use cases

TL;DR

The paper surveys bosonic coding as a framework for robust quantum information processing in continuous-variable CV systems, classifying codes into bosonic stabilizer codes and bosonic Fock-state codes. It details representative constructions such as GKP, GKP-stabilizer, cat, binomial, and number-phase codes, and discusses how infinite dimensionality enables error correction beyond DV limits, including continuous transversal gates and bias-preserving dynamics. It analyzes noise models—loss, dephasing, and displacement—and maps code performance to these channels, highlighting hardware efficiency gains and decoding strategies that leverage analog information. The work emphasizes practical implications for quantum memories and communications, including the capacity for Gaussian-displacement channels and the potential for integrating bosonic and DV approaches to achieve scalable fault-tolerant quantum computation with non-Gaussian resources like GKP states. It also points to open questions, such as thresholds for GKP-based schemes and the broader role of bosonic codes in quantum simulation and topological modeling.

Abstract

Bosonic or continuous-variable coding is a field concerned with robust quantum information processing and communication with electromagnetic signals or mechanical modes. I review bosonic quantum memories, characterizing them as either bosonic stabilizer or bosonic Fock-state codes. I then enumerate various applications of bosonic encodings, four of which circumvent no-go theorems due to the intrinsic infinite-dimensionality of bosonic systems.
Paper Structure (23 sections, 30 equations, 3 figures, 2 tables)

This paper contains 23 sections, 30 equations, 3 figures, 2 tables.

Table of Contents

  1. Introduction & outline
  2. Conventional quantum error correction
  3. Bosonic modes
  4. Bosonic stabilizer codes Barnes2004 attr/Border[0 0 0] user/Subtype /Link /A << /S /URI /URI (https://errorcorrectionzoo.org/c/oscillator_stabilizer) >>
  5. Analog stabilizer codes Lloyd1998Braunstein1998Barnes2004 attr/Border[0 0 0] user/Subtype /Link /A << /S /URI /URI (https://errorcorrectionzoo.org/c/analog_stabilizer) >>
  6. GKP codes Gottesman2001 attr/Border[0 0 0] user/Subtype /Link /A << /S /URI /URI (https://errorcorrectionzoo.org/c/gkp) >>
  7. GKP-stabilizer codes Noh2019a attr/Border[0 0 0] user/Subtype /Link /A << /S /URI /URI (https://errorcorrectionzoo.org/c/gkp-stabilizer) >>
  8. Normalization and precision
  9. Bosonic Fock-state codes attr/Border[0 0 0] user/Subtype /Link /A << /S /URI /URI (https://errorcorrectionzoo.org/c/fock_state) >>
  10. Number-phase codes Grimsmo2019 attr/Border[0 0 0] user/Subtype /Link /A << /S /URI /URI (https://errorcorrectionzoo.org/c/number_phase) >>
  11. Cat codes Leghtas2013b attr/Border[0 0 0] user/Subtype /Link /A << /S /URI /URI (https://errorcorrectionzoo.org/c/cat) >>
  12. Binomial codes bin attr/Border[0 0 0] user/Subtype /Link /A << /S /URI /URI (https://errorcorrectionzoo.org/c/binomial) >>
  13. Chebyshev codes Layden2019 attr/Border[0 0 0] user/Subtype /Link /A << /S /URI /URI (https://errorcorrectionzoo.org/c/chebyshev) >>
  14. Multi-mode Fock-state codes attr/Border[0 0 0] user/Subtype /Link /A << /S /URI /URI (https://errorcorrectionzoo.org/c/fock_state) >>
  15. The fight against physical noise
  16. ...and 8 more sections

Figures (3)

  • Figure 1: (a) GKP codewords are superpositions of alternating position states $x$ and can be similarly formulated for linear and angular systems, i.e., bosonic modes and planar rotors. I sketch position states participating in (b) square-lattice GKP codewords (\ref{['eq:gkpstates']}) and (c)$N=3$ rotor-GKP codewords as well as regions of detectable (yellow) and correctable (green) shifts.
  • Figure 2: Sketch of Wigner function of (a) a phase state and (b) a coherent state in the mode's position-momentum phase space. Sketch of (c) single-mode and (d) two-mode ladders of Fock states with occupation number up to four. Loss operators $a$ and $b$ decrease the occupation number in either mode by one, and the Fock-state spacing provided by Fock-state codes allows for detection and correction of such errors.
  • Figure 3: Three types of common noise channels in bosonic systems --- (a) loss, (b) dephasing, and (c) displacement noise. The effect of each channel on a coherent state (blue circle) in $(x,p)$-phase space is sketched using red arrows. Kraus operators are shown below, with $\chi$ the noise strength, $\ell\geq0$, and $\mathbf{q}=(q_1,q_2)$.