"""Josephson junction components."""
from __future__ import annotations
import gdsfactory as gf
from gdsfactory.component import Component
from gdsfactory.typings import ComponentSpec, CrossSectionSpec, LayerSpec
from klayout.db import DCplxTrans
from qpdk.cells.waveguides import straight
from qpdk.helper import show_components
from qpdk.tech import (
LAYER,
josephson_junction_cross_section_narrow,
josephson_junction_cross_section_wide,
)
[docs]
@gf.cell
def single_josephson_junction_wire(
wide_straight_length: float = 8.3,
narrow_straight_length: float = 0.5,
taper_length: float = 4.7,
cross_section_wide: CrossSectionSpec = josephson_junction_cross_section_wide,
cross_section_narrow: CrossSectionSpec = josephson_junction_cross_section_narrow,
layer_patch: LayerSpec = LAYER.JJ_PATCH,
size_patch: tuple[float, float] = (1.5, 1.0),
) -> Component:
r"""Creates a single wire to use in a Josephson junction.
.. svgbob::
┌───┐
│o1 │━━━━────╶╶╶╶╶ o2
└───┘
wide narrow
Args:
wide_straight_length: Length of the wide straight section in µm.
narrow_straight_length: Length of the narrow straight section in µm.
taper_length: Length of the taper section in µm.
cross_section_wide: Cross-section specification for the wide section.
cross_section_narrow: Cross-section specification for the narrow section.
layer_patch: Layer for the patch that creates the overlap region.
size_patch: Size of the patch that creates the overlap region.
"""
c = Component()
# Widest straight section with patch
wide_straight_ref = c << straight(
length=wide_straight_length, cross_section=cross_section_wide
)
# Add the tapered transition section
taper_ref = c << gf.c.taper_cross_section(
length=taper_length,
cross_section1=cross_section_wide,
cross_section2=cross_section_narrow,
linear=True,
)
# Narrow straight section with overlap
narrow_straight_ref = c << straight(
length=narrow_straight_length, cross_section=cross_section_narrow
)
# Connect all
taper_ref.connect("o1", wide_straight_ref.ports["o2"])
narrow_straight_ref.connect("o1", taper_ref.ports["o2"])
# Add patch to wide section
if layer_patch:
patch = c << gf.components.rectangle(
size=size_patch,
layer=layer_patch,
centered=True,
)
# Overlap with one fourth offset to one side
patch.move(
(wide_straight_ref.dbbox().p1.x - size_patch[0] / 4, wide_straight_ref.y)
)
# Add port at wide end
c.add_port(
port=wide_straight_ref.ports["o1"], name="o1", cross_section=cross_section_wide
)
# Add port at narrow end
c.add_port(
port=narrow_straight_ref.ports["o2"],
name="o2",
cross_section=cross_section_narrow,
)
return c
[docs]
@gf.cell
def josephson_junction(
junction_overlap_displacement: float = 1.8,
wide_straight_length: float = 8.3,
narrow_straight_length: float = 0.5,
taper_length: float = 4.7,
cross_section_wide: CrossSectionSpec = josephson_junction_cross_section_wide,
cross_section_narrow: CrossSectionSpec = josephson_junction_cross_section_narrow,
layer_patch: LayerSpec = LAYER.JJ_PATCH,
size_patch: tuple[float, float] = (1.5, 1.0),
) -> Component:
r"""Creates a single Josephson junction component.
A Josephson junction consists of two superconducting electrodes separated
by a thin insulating barrier allowing tunnelling.
.. svgbob::
right_wide
┌───┐ ╷ overlap
│ │━━━━────╶╶╷╶╶
└───┘ ╷
│
│
┃
┃
┌───┐
│ │
└───┘
left_wide
Args:
junction_overlap_displacement: Displacement of the overlap region in µm.
Measured from the centers of the junction ports.
wide_straight_length: Length of the wide straight section in µm.
narrow_straight_length: Length of the narrow straight section in µm.
taper_length: Length of the taper section in µm.
cross_section_wide: Cross-section specification for the wide section.
cross_section_narrow: Cross-section specification for the narrow section.
layer_patch: Layer for the patch that creates the overlap region.
size_patch: Size of the patch that creates the overlap region.
"""
c = Component()
# Left wire
left_wire = c << single_josephson_junction_wire(
wide_straight_length=wide_straight_length,
narrow_straight_length=narrow_straight_length,
taper_length=taper_length,
cross_section_wide=cross_section_wide,
cross_section_narrow=cross_section_narrow,
layer_patch=layer_patch,
size_patch=size_patch,
)
# Right wire
right_wire = c << single_josephson_junction_wire(
wide_straight_length=wide_straight_length,
narrow_straight_length=narrow_straight_length,
taper_length=taper_length,
cross_section_wide=cross_section_wide,
cross_section_narrow=cross_section_narrow,
layer_patch=layer_patch,
size_patch=size_patch,
)
total_length = wide_straight_length + narrow_straight_length + taper_length
# Position left wire on top of right wire with rotation
left_wire.dcplx_trans = (
right_wire.ports["o2"].dcplx_trans
* DCplxTrans.R90
* DCplxTrans(
-total_length + junction_overlap_displacement,
0,
)
)
right_wire.dcplx_trans *= DCplxTrans(junction_overlap_displacement, 0)
# Add ports at wide ends
c.add_port(
name="left_wide",
port=left_wire.ports["o1"],
)
c.add_port(
name="right_wide",
port=right_wire.ports["o1"],
)
# One port at overlap
c.add_port(
name="overlap",
center=(
left_wire.ports["o2"].dcplx_trans
* DCplxTrans(-junction_overlap_displacement, 0)
).disp.to_p(),
width=left_wire.ports["o2"].width,
orientation=left_wire.ports["o2"].orientation,
layer=left_wire.ports["o2"].layer,
port_type=left_wire.ports["o2"].port_type,
)
# breakpoint()
return c
[docs]
@gf.cell
def squid_junction(
junction_spec: ComponentSpec = josephson_junction,
loop_area: float = 4,
) -> Component:
"""Creates a SQUID (Superconducting Quantum Interference Device) junction component.
A SQUID consists of two Josephson junctions connected in parallel, forming a loop.
See :cite:`clarkeSQUIDHandbook2004` for details.
Args:
junction_spec: Component specification for the Josephson junction component.
loop_area: Area of the SQUID loop in µm².
This does not take into account the junction wire widths.
"""
c = Component()
junction_comp = gf.get_component(junction_spec)
left_junction = c << junction_comp
right_junction = c << junction_comp
# Form a cross by positioning overlaps on top of each other
right_junction.dcplx_trans = (
left_junction.ports["overlap"].dcplx_trans
* DCplxTrans.R90
* DCplxTrans(
-left_junction.xmax
+ (left_junction.xmax - left_junction.ports["overlap"].x),
0,
)
)
# Start adding area by displacing junctions
displacement_xy = loop_area**0.5
right_junction.dcplx_trans *= DCplxTrans((displacement_xy,) * 2)
# Add ports from junctions with descriptive names
for junction_name, junction in [("left", left_junction), ("right", right_junction)]:
for port_side in ["left", "right"]:
port_name = f"{junction_name}_{port_side}_wide"
c.add_port(name=port_name, port=junction.ports[f"{port_side}_wide"])
# Overlaps and their center
c.add_port(name="left_overlap", port=left_junction.ports["overlap"])
c.add_port(name="right_overlap", port=right_junction.ports["overlap"])
c.add_port(
name="loop_center",
center=(
(
left_junction.ports["overlap"].dcplx_trans.disp
+ right_junction.ports["overlap"].dcplx_trans.disp
)
/ 2
).to_p(),
layer=left_junction.ports["overlap"].layer,
width=left_junction.ports["overlap"].width,
)
return c
if __name__ == "__main__":
show_components(josephson_junction, squid_junction)
