Qubitserf

A command‑line tool for computing the minimum distance of quantum codes, with support for CSS codes and parallelized algorithms.

Disclaimer: Qubitserf is in early development. While main functionality is implemented, expect edge cases and performance tuning to evolve.

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Features

• Distance computation using a meet‑in‑the‑middle algorithm (default) with $\mathcal{O}(n^{\lfloor d/2 \rfloor})$ memory, where:

  • $n$ = number of qubits
  • $d$ = code distance

• Brouwer‑Zimmerman algorithm (--bz): constant memory, parallelizable, ideal for large codes.

• CSS‑specific multi‑distance output (--zx): returns both $Z$-distance and $X$-distance.

• Threaded computation (--threads <count>): specify number of worker threads for parallel runs.

• Verbose logging (--verbose or -v): enable detailed progress output.

• Flexible input: read stabilizer generators line by line; terminate input on an empty line or EOF.

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Installation

1. Clone the repository:

   git clone https://github.com/yourusername/qubitserf.git
   cd qubitserf

2. Build:

   make
   make interface

3. Artifacts: The build/ directory will contain:

   • interface : the main executable
   • Supporting libraries and object files

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Usage

./interface [OPTIONS]

1. Prepare input: enter stabilizer generators (one per line) in Pauli notation (I, X, Y, Z), for example:

   ZZIIXZ...  
   XIIZZ...   
   ...        
   <empty line or Ctrl‑D>
   

2. Run with flags (all flags are optional):

   • --bz : Use the Brouwer‑Zimmerman algorithm instead of the default.
   • --zx : For CSS codes only, output Z‑ and X‑distance as two integers.
   • --threads <N> : Parallelize using up to N threads. Must be a positive integer.
   • --verbose, -v : Print detailed progress and diagnostics to stderr.

Notes

• --bz and --zx require CSS codes. The program will error if used on non‑CSS input.
• Input terminates on an empty line or EOF (Ctrl‑D on UNIX, Ctrl‑Z on Windows).

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Examples

Default (meet‑in‑the‑middle) on a CSS code

$ ./interface --zx  
ZZIIIZZIIIII
IXXIIIXXIIII
... (more lines)
<empty line>
5 4

Outputs 5 4, the $Z$- and $X$-distances.

Meet in the middle, parallelized, verbose

$./interface -v --threads 16
ZIIIIIIIZXYYIIYYXIIIII
XIIIIIIIXYZZIIZZYIIIII
IZIIIIIIXXYXYIZXIIIIII
IXIIIIIIYYZYZIXYIIIIII
IIZIIIIIIXXYXYIZXIIIII
IIXIIIIIIYYZYZIXYIIIII
IIIZIIIIXYYYYXXZXIIIII
IIIXIIIIYZZZZYYXYIIIII
IIIIZIIIXZXXYYYYXIIIII
IIIIXIIIYXYYZZZZYIIIII
IIIIIZIIXZIYXYXXIIIIII
IIIIIXIIYXIZYZYYIIIIII
IIIIIIZIIXZIYXYXXIIIII
IIIIIIXIIYXIZYZYYIIIII
IIIIIIIZXYYIIYYXZIIIII
IIIIIIIXYZZIIZZYXIIIII
IIIIIIIIIIIIIIIIIZIIII
IIIIIIIIIIIIIIIIIIZIII
IIIIIIIIIIIIIIIIIIIZII
IIIIIIIIIIIIIIIIIIIIZI
IIIIIIIIIIIIIIIIIIIIIZ

Distance bound: >1
Elapsed:[15ms] 
Distance bound: >2
Elapsed:[0ms] 
Distance bound: >3
Elapsed:[15ms] 
Distance bound: >4
Elapsed:[9ms] 
Distance bound: >5
Elapsed:[119ms] 
Distance bound: >6
Elapsed:[101ms] 
Distance: =7
Elapsed:[1.087s] 

Non-CSS code distance

$ ./interface
ZZIIIZIIIZ
IZIZIZIZIZ
... (more lines)
<empty line>
4

Prints the single distance 4 for a non-CSS code.