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Quantifying Nonlocality: How Outperforming Local Quantum Codes Is Expensive
Nouédyn Baspin1, Anirudh Krishna2
1Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1.
Implementing quantum low-density parity-check (LDPC) codes requires understanding the trade-offs between code parameters and interaction types. This study quantifies the number of long-range interactions needed for quantum LDPC codes with specific dimensions and distances.
Area of Science:
- Quantum Information Science
- Quantum Error Correction
- Theoretical Computer Science
Background:
- Quantum low-density parity-check (LDPC) codes offer a path to efficient, scalable quantum circuit construction.
- Previous work established limitations on quantum LDPC codes using only local interactions for dimension (k) and distance (d).
Purpose of the Study:
- To investigate the number of long-range interactions necessary for implementing quantum LDPC codes with specific parameters (k, d).
- To establish quantitative bounds on code parameters based on limited long-range connectivity.
Main Methods:
- Analysis of 2D quantum LDPC codes.
- Derivation of lower bounds on the number and length of interactions required.
- Application to a stacked architecture model.
Main Results:
- A quantum LDPC code with distance d∝n^{1/2+ϵ} requires Ω(n^{1/2+ϵ}) long-range interactions of length Ω[over ˜](n^{ϵ}).
- A code with k∝n and d∝n^{α} necessitates Ω[over ˜](n) interactions of length Ω[over ˜](n^{α/2}).
- Limited long-range connectivity in a stacked architecture imposes bounds on achievable distance and code dimension.
Conclusions:
- The number of long-range interactions is a critical factor in the practical implementation of quantum LDPC codes.
- Understanding these interaction requirements is essential for designing efficient and scalable quantum error correction schemes.
- The findings provide quantitative insights into the resource costs associated with achieving desired code performance.
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