Spectral Filter Example

This example demonstrates how spectral filtering is applied to a state using SpectralFilter model, we also make use of NumberStateSource to generate the state.

from __future__ import annotations
from symop.devices.models import SpectralFilter, NumberStateSource
from symop.modes.labels import Path, Polarization
from symop.modes.envelopes import GaussianEnvelope
from symop.modes.transfer import GaussianLowpass
from symop.polynomial.state import KetPolyState

# Visualization Package
import symop.viz as VI

Setup

set up a mode labels and then the single photon source together with filter defined by a transfer function.

src_env = GaussianEnvelope(omega0=100.0, sigma=50.0, tau=0.0)
src_pol = Polarization.H()

src_dev = NumberStateSource(envelope=src_env, polarization=src_pol, n=1)

tf = GaussianLowpass(w0=100.0, sigma_w=0.01)
filt_dev = SpectralFilter(transfer=tf)

1) Generate the state

• Generate the vacuum state for the source to populate

• For populating the vacuum __call__() can be used or .apply()

vac = KetPolyState.vacuum()
single_photon_state = src_dev(
    vac,
    ports={"out": Path("src_out")},
).with_label("in")

2) Use filtering device to filter

filtered_state = filt_dev(
    single_photon_state,
    ports={
        "in": Path("src_out"),  # Path leading from the source to filter
        "out": Path("filt_out"),
    },
).with_label("filt")

3) Inspect the state after filtering

VI.plot(single_photon_state)
VI.plot(filtered_state)

• 
• 

<Figure size 900x440 with 2 Axes>

3a) Display the input state

VI.display(single_photon_state)

3b) Display the filtered state

VI.display(filtered_state)