Safe Haskell  None 

Authors: Keith Kim, Peter LeFanu Lumsdaine, Alexandr Virodov
An implementation of Hallgren’s Class Number algorithm. This algorithm computes various invariants of a real quadratic number field K = ℚ(√Δ), notably the class number and the structure of the class group CL(K). The field K is specified by its discriminant Δ, the main input to the algorithm.
The algorithm may also be adapted to other problems from algebraic number theory, including Pell's equation (finding integer solutions to x ^{2} − dy ^{2} = 1, for nonsquare d) and the principal ideal problem (determining whether an ideal of a number field is principal, and finding a generator if so).
The present implementation falls into five stages, which we will refer to throughout the documentation:
 Approximate the regulator of K, to low precision, using a version of the the (quantum) HSP algorithm.
 Classically, refine the approximation from part 1 to higher precision.
 Classically compute a small generating set for the class group, using the value of the regulator from part 2.
 Compute relations for these generators, again using a version of the HSP algorithm.
 Classically compute from these the structure of the class group, and hence the class number.
Further details are given in the documentation of individual modules.
The algorithm and its mathematical background are described in:
 Sean Hallgren, "Polynomialtime quantum algorithms for Pell’s equation and the principal ideal problem", in STOC ’02: Proceedings of the thirtyfourth annual ACM symposium on Theory of computing, pp. 653–658, 2002. (Also published in J. ACM, 54(1), 2007.)
 Richard Jozsa, "Quantum computation in algebraic number theory: Hallgren’s efficient quantum algorithm for solving Pell’s equation." Annals of Physics, 306:241–279, February 2003; also available as http://arxiv.org/abs/quantph/0302134. All references in documentation refer to arXiv version.
 Daniel Haase and Helmut Maier, "Quantum algorithms for number fields." Fortschr. Phys., 54(8):866–881, 2006.
The present implementation is based on a detailed algorithm specification that was provided to us by the IARPA QCS program and written by Brian J. Matt, Durward McDonell, and David Zaret.
Modules:
 Algorithms.CL.Main: Command line interface.
 Algorithms.CL.Auxiliary: Generalpurpose functions required in Hallgren’s algorithm.
 Algorithms.CL.Types: Specialized classical and quantum datatypes used in Hallgren’s algorithm, and basic functions on these types.
 Algorithms.CL.CL: The highlevel structure of Hallgren’s algorithm.
 Algorithms.CL.RegulatorClassical: A classical implementation of the functions and operations of stages 1–4.
 Algorithms.CL.RegulatorQuantum: A quantum implementation of the functions required for stages 1 and 4
 Algorithms.CL.SmithReduction: Matrices, and reduction to Smith Normal Form, for Stage 5.
 Algorithms.CL.Test: Functions to test components of the present implementation, using classical computation.
 data WhatToShow
 data Subroutine
 subroutine_enum :: [(String, Subroutine)]
 data Options = Options {}
 default_options :: Options
 show_default :: Show a => (Options > a) > String
 options :: [OptDescr (Options > IO Options)]
 dopts :: [String] > IO Options
 usage :: IO ()
 main :: IO ()
 main_stage1 :: Options > IO ()
 main_stage4 :: Options > IO ()
 main_sub :: Options > IO ()
Command line interface
This module provides a command line interface for Hallgren’s Class Number algorithm. This allows the user, for example, to print or simulate the circuits used in quantum portions of the algorithm, or to run small instances of the algorithm in a classical implementation.
Sample invocations:
>>>
./cl R
Compute, classically, the regulator of ℚ[√Δ], with Δ = 28 (default value).
>>>
./cl P d 17
Compute, classically, the fundamental solution of Pell’s equation x^{2} − dy^{2} = 1 with d = Δ = 17.
>>>
./cl S fn d 5 f eps > cl_fn_d5.eps
Produce an .eps file of the quantum circuit implementing the pseudoperiodic function f_{N} used for regulator estimation, for Δ = 5
>>>
./cl S starprod d 60 f gatecount
Give gatecount for the quantum circuit implementing the starproduct on ideals, for Δ = 17
>>>
./cl help
Print detailed usage information.
Option processing
data WhatToShow Source #
An enumeration type for determining what the main function should do.
Stage1  Show the circuit for stage 1 of the algorithm 
Stage4  Show the circuit for stage 4 of the algorithm 
Sub  Show the circuit for a specific quantum subroutine 
Regulator  Classically, find the regulator 
FundamentalUnit  Classically, find the fundamental unit 
PellSolution  Classically, find the fundamental solution of Pell’s equation 
data Subroutine Source #
An enumeration type for selecting a subroutine.
subroutine_enum :: [(String, Subroutine)] Source #
An enumeration of available subroutines. (Compare format_enum
, gatebase_enum
.)
A data type to hold values set by command line options.
Options  

default_options :: Options Source #
The default options.
options :: [OptDescr (Options > IO Options)] Source #
The list of command line options, in the format required by getOpt
.
dopts :: [String] > IO Options Source #
Process argvstyle command line options into an Options
structure.
The CL circuit generation main function
main_stage1 :: Options > IO () Source #
Main function for outputting the circuit for stage 1 of Hallgren’s algorithm.
main_stage4 :: Options > IO () Source #
Main function for outputting the circuit for stage 4 of Hallgren’s algorithm.