Closed Hugh-888 closed 5 days ago
large squeezing parameter r leads to non-positive definite covariance matrix
nmode = 2 circ = dq.QumodeCircuit(nmode=nmode, init_state='vac', cutoff=3, backend='gaussian', basis=True) circ.s([0], r=11) st = circ() circ.draw() re = circ.measure_homodyne(wires=[0], shots=1) re
Maybe we can add an identity matrix of epsilon=1e-7 or epsilon=1e-15 to the covariance matrix if the minimum value of its diagonal elements is too small according to the dtype.
epsilon=1e-7
epsilon=1e-15
dtype
Problem
large squeezing parameter r leads to non-positive definite covariance matrix
code