R/sigmaZ.R

In QGameTheory: Quantum Game Theory Simulator

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#                             PAULI MATRIX                                   #
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#' @title
#' Pauli-Z gate
#'
#' @description
#' This function operates the Pauli-Z gate on a conformable input matrix or a vector.
#'
#' @param n a vector/matrix
#'
#' @usage
#' sigmaZ(n)
#'
#' @return A matrix or a vector after performing the Pauli-Z gate operation on a conformable input matrix or a vector.
#'
#' @references
#' \url{https://en.wikipedia.org/wiki/Quantum_logic_gate}\cr
#' \url{http://www2.optics.rochester.edu/~stroud/presentations/muthukrishnan991/LogicGates.pdf}\cr
#' \url{http://www.physics.udel.edu/~msafrono/650/Lecture%204%20-%205.pdf}\cr
#'
#' @examples
#' init()
#' sigmaZ(Q$I2)
#' sigmaZ(Hadamard(Q$I2))
#' sigmaZ(Q$Q0)
#'
#' @export
#'
sigmaZ <- function(n){
  Z <- matrix(c(1, 0, 0, -1), ncol=2, byrow=TRUE)
  return (Z %*% n)
}