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MpIBcCorrelation

Calculate the two-point correlation function from an IBC time-evolution simulation.

Synopsis

mp-ibc-correlation [options] -w <prefix> -t <timestep>

Options

--help

Show help message.

-c, --cart

Show the results in Cartesian coordinates.

-p, --polar

Show the results in polar coordinates.

-r, --real

Show the real part of the result.

-i, --imag

Show the imaginary part of the result.

-m, --mag

Show the magnitude part of the result.

-a, --arg

Show the argument part of the result.

--radians

Show the argument in radians.

--conj

Use complex conjugation to calculate the correlation function up to {$t = 2T$}.

--string

(2D cylinders) Calculate the {$y$} dependence of the correlation function using this string operator representation of the cylinder rotation operator.

-w, --wavefunction

Prefix for the input wavefunction filenames, which are of the form [prefix].t[t] (required).

-t, --timestep

The timestep (required).

--digits

Force the input filenames to have this many decimal places.

-n, --num-timesteps

The number of timesteps to calculate.

--xmin

The minimum value of x to calculate (default 0).

-x, --xmax

The maximum value of x to calculate (default 0).

-y, --ymax

(2D cylinders) The maximum value of y to calculate (requires --string).

--ucsize

The unit cell size to use to determine how many sites to shift for each x step (defaults to the left boundary unit cell size).

--unityepsilon

The error tolerance for transfer matrix eigenvalues near unity (default 1e-12).

--phasefix

Subtract this value from the phase (in degrees, or radians if --radians is specfied).

--quiet

Do not print the column headings.

-v, --verbose

Increase verbosity.

Description

This tool calculates two-point correlation functions for the form {$$C(x,t) = \langle \Psi_0 | O_x(t) O_0(0)^\dagger | \Psi_0 \rangle.$$} If we calculate a time-evolution simulation {$| \Psi(t) \rangle = \mathrm{e}^{-\mathrm{i}Ht} O_0^\dagger | \Psi_0 \rangle$}, we can calculate this two-point correlation function by {$$C(x,t) = \langle \Psi(0) | T^x | \Psi(t) \rangle,$$} where {$T^x$} is the translation operator by {$x$} sites.

Furthermore, we can rearrange this to obtain {$$C(x,t) = \langle \Psi(-t/2) | T^x | \Psi(t/2) \rangle,$$} and if the initial state is time-reversal symmetric, we can obtain {$|\Psi(-t/2)\rangle$} from the complex conjugate of {$|\Psi(t/2)\rangle$}. Hence, using this technique, we can calculate the correlation function up to {$t = 2T$} from a time evolution simulation that only goes to {$t = T$}.

Notes

  • This tool is essentially the same results as using mp-ibc-overlap multiple times, but we can reuse the transfer matrix eigenvalues for each calculation if we are using the complex conjugation trick.
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Page last modified on November 01, 2023, at 08:22 AM