From 6338ed4fa9f08700d14c17be1b48eb6e3f41c916 Mon Sep 17 00:00:00 2001
From: elib20 <53090166+elib20@users.noreply.github.com>
Date: Fri, 17 Dec 2021 18:06:46 -0500
Subject: [PATCH 1/9] Adds rectangular GKP states
- Adds a parameter, alpha, to specify peak spacing of the GKP state
- Modifies both fock and bosonic backends
---
.../backends/bosonicbackend/backend.py | 26 +++++++--
.../backends/fockbackend/backend.py | 16 ++++--
.../backends/fockbackend/circuit.py | 8 ++-
strawberryfields/backends/fockbackend/ops.py | 30 +++++-----
strawberryfields/ops.py | 11 +++-
tests/backend/test_bosonic_backend.py | 57 +++++++++++++++++++
untitled0.py | 43 ++++++++++++++
7 files changed, 163 insertions(+), 28 deletions(-)
create mode 100644 untitled0.py
diff --git a/strawberryfields/backends/bosonicbackend/backend.py b/strawberryfields/backends/bosonicbackend/backend.py
index e72da5769..fa44c1e33 100644
--- a/strawberryfields/backends/bosonicbackend/backend.py
+++ b/strawberryfields/backends/bosonicbackend/backend.py
@@ -535,7 +535,9 @@ def prepare_cat_real_rep(self, alpha, phi, ampl_cutoff, D):
return weights, means, cov
- def prepare_gkp(self, state, epsilon, ampl_cutoff, representation="real", shape="square"):
+ def prepare_gkp(
+ self, state, epsilon, ampl_cutoff, representation="real", shape="square", alpha=1
+ ):
r"""Prepares the arrays of weights, means and covs for a finite energy GKP state.
GKP states are qubits, with the qubit state defined by:
@@ -550,6 +552,7 @@ def prepare_gkp(self, state, epsilon, ampl_cutoff, representation="real", shape=
ampl_cutoff (float): this determines how many terms to keep
representation (str): ``'real'`` or ``'complex'`` reprsentation
shape (str): shape of the lattice; default 'square'
+ alpha (float): peak spacing in q is given by sqrt(alpha * pi)
Returns:
tuple: arrays of the weights, means and covariances for the state
@@ -561,12 +564,19 @@ def prepare_gkp(self, state, epsilon, ampl_cutoff, representation="real", shape=
if representation == "complex":
raise NotImplementedError("The complex description of GKP is not implemented")
- if shape != "square":
- raise NotImplementedError("Only square GKP are implemented for now")
+ if shape not in ["square", "rectangular"]:
+ raise NotImplementedError("Only square and rectangular GKP are implemented.")
+
+ if shape == "square":
+ if alpha != 1:
+ raise ValueError(
+ "For square GKPs, alpha must be 1. For alpha not equal to "
+ + "1, use shape='rectangular'."
+ )
theta, phi = state[0], state[1]
- def coeff(peak_loc):
+ def coeff(peak_loc, alpha):
"""Returns the value of the weight for a given peak.
Args:
@@ -605,7 +615,7 @@ def coeff(peak_loc):
prefactor = np.exp(
-np.pi
* 0.25
- * (l ** 2 + m ** 2)
+ * ((l * alpha) ** 2 + (m / alpha) ** 2)
* (1 - np.exp(-2 * epsilon))
/ (1 + np.exp(-2 * epsilon))
)
@@ -644,7 +654,7 @@ def coeff(peak_loc):
)
# Calculate the weights for each peak
- weights = coeff(means)
+ weights = coeff(means, np.sqrt(alpha))
filt = abs(weights) > ampl_cutoff
weights = weights[filt]
@@ -652,7 +662,11 @@ def coeff(peak_loc):
# Apply finite energy effect to means
means = means[filt]
+ means[:, 0] *= np.sqrt(alpha)
+ means[:, 1] /= np.sqrt(alpha)
+
means *= 0.5 * damping * np.sqrt(np.pi * self.circuit.hbar)
+
# Covariances all the same
covs = (
0.5
diff --git a/strawberryfields/backends/fockbackend/backend.py b/strawberryfields/backends/fockbackend/backend.py
index 80ba64580..b01427c8b 100644
--- a/strawberryfields/backends/fockbackend/backend.py
+++ b/strawberryfields/backends/fockbackend/backend.py
@@ -292,7 +292,7 @@ def measure_fock(self, modes, shots=1, select=None, **kwargs):
return self.circuit.measure_fock(self._remap_modes(modes), select=select)
def prepare_gkp(
- self, state, epsilon, ampl_cutoff, representation="real", shape="square", mode=None
+ self, state, epsilon, ampl_cutoff, representation="real", shape="square", alpha=1, mode=None
):
r"""Prepares the Fock representation of a finite energy GKP state.
@@ -308,6 +308,7 @@ def prepare_gkp(
amplcutoff (float): this determines how many terms to keep
representation (str): ``'real'`` or ``'complex'`` reprsentation
shape (str): shape of the lattice; default 'square'
+ alpha (float): peak spacing in q is given by sqrt(alpha * pi)
Returns:
tuple: arrays of the weights, means and covariances for the state
@@ -319,8 +320,15 @@ def prepare_gkp(
if representation == "complex":
raise NotImplementedError("The complex description of GKP is not implemented")
- if shape != "square":
- raise NotImplementedError("Only square GKP are implemented for now")
+ if shape not in ["square", "rectangular"]:
+ raise NotImplementedError("Only square and rectangular GKP are implemented.")
+
+ if shape == "square":
+ if alpha != 1:
+ raise ValueError(
+ "For square GKPs, alpha must be 1. For alpha not equal to "
+ + "1, use shape='rectangular'."
+ )
theta, phi = state[0], state[1]
- self.circuit.prepare_gkp(theta, phi, epsilon, ampl_cutoff, self._remap_modes(mode))
+ self.circuit.prepare_gkp(theta, phi, epsilon, ampl_cutoff, alpha, self._remap_modes(mode))
diff --git a/strawberryfields/backends/fockbackend/circuit.py b/strawberryfields/backends/fockbackend/circuit.py
index 699dd219f..525de9efe 100644
--- a/strawberryfields/backends/fockbackend/circuit.py
+++ b/strawberryfields/backends/fockbackend/circuit.py
@@ -793,13 +793,15 @@ def measure_homodyne(self, phi, mode, select=None, **kwargs):
# `homodyne_sample` will always be a single value since multiple shots is not supported
return np.array([[homodyne_sample]])
- def prepare_gkp(self, theta, phi, epsilon, ampl_cutoff, mode):
+ def prepare_gkp(self, theta, phi, epsilon, alpha, ampl_cutoff, mode):
"""
Prepares a mode in a GKP state.
"""
if self._pure:
- self.prepare(ops.square_gkp_state(theta, phi, epsilon, ampl_cutoff, self._trunc), mode)
+ self.prepare(
+ ops.rect_gkp_state(theta, phi, epsilon, alpha, ampl_cutoff, self._trunc), mode
+ )
else:
- st = ops.square_gkp_state(theta, phi, epsilon, ampl_cutoff, self._trunc)
+ st = ops.rect_gkp_state(theta, phi, epsilon, alpha, ampl_cutoff, self._trunc)
self.prepare(np.outer(st, st.conjugate()), mode)
diff --git a/strawberryfields/backends/fockbackend/ops.py b/strawberryfields/backends/fockbackend/ops.py
index 372af7c23..801cc6e9b 100644
--- a/strawberryfields/backends/fockbackend/ops.py
+++ b/strawberryfields/backends/fockbackend/ops.py
@@ -500,7 +500,7 @@ def hermiteVals(q_mag, num_bins, m_omega_over_hbar, trunc):
return q_tensor, Hvals
-def gkp_displacements(t, k, epsilon):
+def gkp_displacements(t, k, epsilon, alpha):
"""
Helper function to generate the displacements parameters associated with the teeth of
GKP computational basis state k.
@@ -509,14 +509,15 @@ def gkp_displacements(t, k, epsilon):
t (array): the teeth of GKP computational basis
k (int): a computational basis state label, can be either 0 or 1
epsilon (float): finite energy parameter of the state
+ alpha (float): peak spacing in q is given by sqrt(alpha * pi)
Returns:
array: the displacements
"""
- return np.sqrt(0.5 * np.pi) * (2 * t + k) / np.cosh(epsilon)
+ return np.sqrt(0.5 * np.pi * alpha) * (2 * t + k) / np.cosh(epsilon)
-def gkp_coeffs(t, k, epsilon):
+def gkp_coeffs(t, k, epsilon, alpha):
"""
Helper function to generate the coefficient parameters associated with the teeth of
GKP computational basis state k.
@@ -525,22 +526,24 @@ def gkp_coeffs(t, k, epsilon):
t (array): the teeth of GKP computational basis
k (int): a computational basis state label, can be either 0 or 1
epsilon (float): finite energy parameter of the state
+ alpha (float): peak spacing in q is given by sqrt(alpha * pi)
Returns:
array: the coefficients
"""
- return np.exp(-0.5 * np.pi * np.tanh(epsilon) * (k + 2 * t) ** 2)
+ return np.exp(-0.5 * np.pi * alpha * np.tanh(epsilon) * (k + 2 * t) ** 2)
@functools.lru_cache()
-def square_gkp_basis_state(i, epsilon, ampl_cutoff, cutoff):
+def rect_gkp_basis_state(i, epsilon, ampl_cutoff, alpha, cutoff):
"""
- Generate the Fock expansion of a (subnormalized) computational GKP basis state. Normalization occurs in the ``square_gkp_state`` method.
+ Generate the Fock expansion of a (subnormalized) computational GKP basis state. Normalization occurs in the ``rect_gkp_state`` method.
Args:
i (int): a computational basis state label, can be either 0 or 1
epsilon (float): finite energy parameter of the state
ampl_cutoff (float): this determines how many terms to keep in the Hilbert space expansion
+ alpha (float): peak spacing in q is given by sqrt(alpha * pi)
cutoff (int): Fock space truncation
Returns
@@ -548,16 +551,16 @@ def square_gkp_basis_state(i, epsilon, ampl_cutoff, cutoff):
"""
z_max = int(np.ceil(np.sqrt(-0.25 / np.pi * np.log(ampl_cutoff) / np.tanh(epsilon))))
- coeffs = [gkp_coeffs(t, i, epsilon) for t in range(-z_max, z_max + 1)]
+ coeffs = [gkp_coeffs(t, i, epsilon, alpha) for t in range(-z_max, z_max + 1)]
r = -0.5 * np.log(np.tanh(epsilon))
- alphas = [gkp_displacements(t, i, epsilon) for t in range(-z_max, z_max + 1)]
- num_kets = len(alphas)
- ket = [coeffs[j] * displacedSqueezed(alphas[j], 0, r, 0, cutoff) for j in range(num_kets)]
+ disps = [gkp_displacements(t, i, epsilon, alpha) for t in range(-z_max, z_max + 1)]
+ num_kets = len(disps)
+ ket = [coeffs[j] * displacedSqueezed(disps[j], 0, r, 0, cutoff) for j in range(num_kets)]
return sum(ket)
@functools.lru_cache()
-def square_gkp_state(theta, phi, epsilon, ampl_cutoff, cutoff):
+def rect_gkp_state(theta, phi, epsilon, ampl_cutoff, alpha, cutoff):
r"""
Generate the Fock expansion of an abitrary GKP state parametrized as
:math:`|\psi\rangle = \cos{\tfrac{\theta}{2}} \vert 0 \rangle_{\rm gkp} + e^{-i \phi} \sin{\tfrac{\theta}{2}} \vert 1 \rangle_{\rm gkp}`.
@@ -567,6 +570,7 @@ def square_gkp_state(theta, phi, epsilon, ampl_cutoff, cutoff):
phi (float): the longitude with respect to the x-axis in the Bloch sphere
epsilon (float): finite energy parameter of the state
ampl_cutoff (float): this determines how many terms to keep
+ alpha (float): peak spacing in q is given by sqrt(alpha * pi)
cutoff (int): Fock space truncation
Returns:
@@ -574,8 +578,8 @@ def square_gkp_state(theta, phi, epsilon, ampl_cutoff, cutoff):
"""
qubit_coeff0 = np.cos(theta / 2)
qubit_coeff1 = np.sin(theta / 2) * np.exp(-1j * phi)
- ket0 = square_gkp_basis_state(0, epsilon, ampl_cutoff, cutoff)
- ket1 = square_gkp_basis_state(1, epsilon, ampl_cutoff, cutoff)
+ ket0 = rect_gkp_basis_state(0, epsilon, ampl_cutoff, alpha, cutoff)
+ ket1 = rect_gkp_basis_state(1, epsilon, ampl_cutoff, alpha, cutoff)
ket = qubit_coeff0 * ket0 + qubit_coeff1 * ket1
ket /= np.linalg.norm(ket)
return ket
diff --git a/strawberryfields/ops.py b/strawberryfields/ops.py
index 9fa8f44b5..0706c464d 100644
--- a/strawberryfields/ops.py
+++ b/strawberryfields/ops.py
@@ -912,14 +912,21 @@ class GKP(Preparation):
cutoff (float): this determines how many terms to keep
representation (str): ``'real'`` or ``'complex'`` reprsentation
shape (str): shape of the lattice; default ``'square'``
+ alpha (float): peak spacing in q is given by sqrt(alpha * pi)
"""
def __init__(
- self, state=None, epsilon=0.2, ampl_cutoff=1e-12, representation="real", shape="square"
+ self,
+ state=None,
+ epsilon=0.2,
+ ampl_cutoff=1e-12,
+ representation="real",
+ shape="square",
+ alpha=1,
):
if state is None:
state = [0, 0]
- super().__init__([state, epsilon, ampl_cutoff, representation, shape])
+ super().__init__([state, epsilon, ampl_cutoff, representation, shape, alpha])
def _apply(self, reg, backend, **kwargs):
backend.prepare_gkp(*self.p, mode=reg[0])
diff --git a/tests/backend/test_bosonic_backend.py b/tests/backend/test_bosonic_backend.py
index 179d9b2db..d0919a8a4 100644
--- a/tests/backend/test_bosonic_backend.py
+++ b/tests/backend/test_bosonic_backend.py
@@ -508,6 +508,35 @@ def test_gkp_complex(self):
backend = bosonic.BosonicBackend()
with pytest.raises(NotImplementedError):
backend.run_prog(prog)
+
+ @pytest.mark.parametrize("eps", EPS_VALS)
+ def test_sensor_gkp(self, eps):
+ r"""Checks that the GKP sensor state is invariant under Fourier."""
+ x = np.linspace(-3 * np.sqrt(np.pi), 3 * np.sqrt(np.pi), 40)
+ p = np.copy(x)
+
+ # Prepare GKP 0 and apply Hadamard
+ prog_sensor = sf.Program(1)
+ with prog_sensor.context as q:
+ sf.ops.GKP(state=[np.pi/2,0], epsilon=eps, shape="rectangular", alpha=2) | q[0]
+
+ backend_sensor = bosonic.BosonicBackend()
+ backend_sensor.run_prog(prog_sensor)
+ state_sensor = backend_sensor.state()
+ wigner_sensor = state_sensor.wigner(0, x, p)
+
+ # Prepare GKP +
+ prog_sensor_F = sf.Program(1)
+ with prog_sensor_F.context as qF:
+ sf.ops.GKP(state=[np.pi/2,0], epsilon=eps, shape="rectangular", alpha=2) | qF[0]
+ sf.ops.Rgate(np.pi / 2) | qF[0]
+
+ backend_sensor_F = bosonic.BosonicBackend()
+ backend_sensor_F.run_prog(prog_sensor_F)
+ state_sensor_F = backend_sensor_F.state()
+ wigner_sensor_F = state_sensor_F.wigner(0, x, p)
+
+ assert np.allclose(wigner_sensor, wigner_sensor_F)
@pytest.mark.parametrize("fock_eps", [0.1,0.2,0.3])
def test_gkp_wigner_compare_backends(self, fock_eps):
@@ -535,6 +564,34 @@ def test_gkp_wigner_compare_backends(self, fock_eps):
gkp_bosonic = eng_bosonic.run(prog_bosonic).state
W_bosonic = gkp_bosonic.wigner(0, xvec, xvec)
assert np.allclose(W_fock, W_bosonic)
+
+ @pytest.mark.parametrize("fock_eps", [0.1,0.2,0.3])
+ @pytest.mark.parametrize("rect_ratio", [0.8,1,1.5])
+ def test_rect_gkp_wigner_compare_backends(self, fock_eps, rect_ratio):
+ """Test correct Wigner function are generated by comparing fock and bosonic outputs.
+ Since the fock backend cannot simulate very small epsilon, we restrict to fock_eps>0.1."""
+ theta = np.pi / 8
+ phi = np.pi / 6
+ ket = [theta, phi]
+ xvec = np.linspace(-1, 1, 200)
+ prog_fock = sf.Program(1)
+ with prog_fock.context as q:
+ sf.ops.GKP(epsilon=fock_eps, state=ket, shape="rectangular", alpha=rect_ratio) | q
+ cutoff = 100
+ hbar = 2
+ eng_fock = sf.Engine("fock", backend_options={"cutoff_dim": cutoff, "hbar": hbar})
+ gkp_fock = eng_fock.run(prog_fock).state
+ W_fock = gkp_fock.wigner(0, xvec, xvec)
+
+ prog_bosonic = sf.Program(1)
+
+ with prog_bosonic.context as q:
+ sf.ops.GKP(epsilon=fock_eps, state=ket, shape="rectangular", alpha=rect_ratio) | q
+ hbar = 2
+ eng_bosonic = sf.Engine("bosonic", backend_options={"hbar": hbar})
+ gkp_bosonic = eng_bosonic.run(prog_bosonic).state
+ W_bosonic = gkp_bosonic.wigner(0, xvec, xvec)
+ assert np.allclose(W_fock, W_bosonic)
class TestBosonicUserSpecifiedState:
diff --git a/untitled0.py b/untitled0.py
new file mode 100644
index 000000000..b089544f6
--- /dev/null
+++ b/untitled0.py
@@ -0,0 +1,43 @@
+# -*- coding: utf-8 -*-
+"""
+Created on Fri Dec 17 15:18:59 2021
+
+@author: Xanadu
+"""
+
+import strawberryfields as sf
+import numpy as np
+import pylab as plt
+
+fock_eps = 0.2
+alpha = 1.2
+xvec = np.linspace(-5, 5, 200)
+
+prog_fock = sf.Program(1)
+with prog_fock.context as q:
+ sf.ops.GKP(epsilon=fock_eps, state=[np.pi/2,0], shape="rectangular", alpha=alpha) | q
+cutoff = 40
+sf.hbar = 1
+eng_fock = sf.Engine("fock", backend_options={"cutoff_dim": cutoff})
+gkp_fock = eng_fock.run(prog_fock).state
+W_fock = gkp_fock.wigner(0, xvec, xvec)
+
+prog_bosonic = sf.Program(1)
+
+with prog_bosonic.context as q:
+ sf.ops.GKP(epsilon=fock_eps, state = [np.pi/2,0], shape="rectangular", alpha=alpha) | q
+sf.hbar = 1
+eng_bosonic = sf.Engine("bosonic")
+gkp_bosonic = eng_bosonic.run(prog_bosonic).state
+W_bosonic = gkp_bosonic.wigner(0, xvec, xvec)
+
+
+plt.contourf(xvec/np.sqrt(np.pi*sf.hbar*2),xvec/np.sqrt(np.pi*sf.hbar*2),W_fock,levels=50)
+plt.show()
+
+plt.contourf(xvec/np.sqrt(np.pi*sf.hbar*2),xvec/np.sqrt(np.pi*sf.hbar*2),W_bosonic,levels=50)
+plt.show()
+
+plt.contourf(xvec/np.sqrt(np.pi*sf.hbar*2),xvec/np.sqrt(np.pi*sf.hbar*2),np.log(abs(W_fock-W_bosonic)),levels=50)
+plt.colorbar()
+plt.show()
\ No newline at end of file
From 7c70407795e198fbe2af8c29506186ac04411f04 Mon Sep 17 00:00:00 2001
From: elib20 <53090166+elib20@users.noreply.github.com>
Date: Fri, 17 Dec 2021 18:21:44 -0500
Subject: [PATCH 2/9] Delete untitled0.py
---
untitled0.py | 43 -------------------------------------------
1 file changed, 43 deletions(-)
delete mode 100644 untitled0.py
diff --git a/untitled0.py b/untitled0.py
deleted file mode 100644
index b089544f6..000000000
--- a/untitled0.py
+++ /dev/null
@@ -1,43 +0,0 @@
-# -*- coding: utf-8 -*-
-"""
-Created on Fri Dec 17 15:18:59 2021
-
-@author: Xanadu
-"""
-
-import strawberryfields as sf
-import numpy as np
-import pylab as plt
-
-fock_eps = 0.2
-alpha = 1.2
-xvec = np.linspace(-5, 5, 200)
-
-prog_fock = sf.Program(1)
-with prog_fock.context as q:
- sf.ops.GKP(epsilon=fock_eps, state=[np.pi/2,0], shape="rectangular", alpha=alpha) | q
-cutoff = 40
-sf.hbar = 1
-eng_fock = sf.Engine("fock", backend_options={"cutoff_dim": cutoff})
-gkp_fock = eng_fock.run(prog_fock).state
-W_fock = gkp_fock.wigner(0, xvec, xvec)
-
-prog_bosonic = sf.Program(1)
-
-with prog_bosonic.context as q:
- sf.ops.GKP(epsilon=fock_eps, state = [np.pi/2,0], shape="rectangular", alpha=alpha) | q
-sf.hbar = 1
-eng_bosonic = sf.Engine("bosonic")
-gkp_bosonic = eng_bosonic.run(prog_bosonic).state
-W_bosonic = gkp_bosonic.wigner(0, xvec, xvec)
-
-
-plt.contourf(xvec/np.sqrt(np.pi*sf.hbar*2),xvec/np.sqrt(np.pi*sf.hbar*2),W_fock,levels=50)
-plt.show()
-
-plt.contourf(xvec/np.sqrt(np.pi*sf.hbar*2),xvec/np.sqrt(np.pi*sf.hbar*2),W_bosonic,levels=50)
-plt.show()
-
-plt.contourf(xvec/np.sqrt(np.pi*sf.hbar*2),xvec/np.sqrt(np.pi*sf.hbar*2),np.log(abs(W_fock-W_bosonic)),levels=50)
-plt.colorbar()
-plt.show()
\ No newline at end of file
From 26c5b88b8a1c2dff4a37e71ed70f670b16b69457 Mon Sep 17 00:00:00 2001
From: elib20 <53090166+elib20@users.noreply.github.com>
Date: Fri, 17 Dec 2021 18:28:11 -0500
Subject: [PATCH 3/9] Ran black + CHANGELOG
---
.github/CHANGELOG.md | 14 ++++++++++++++
tests/backend/test_bosonic_backend.py | 12 ++++++------
2 files changed, 20 insertions(+), 6 deletions(-)
diff --git a/.github/CHANGELOG.md b/.github/CHANGELOG.md
index 0025978cc..13b2bc4f6 100644
--- a/.github/CHANGELOG.md
+++ b/.github/CHANGELOG.md
@@ -2,6 +2,18 @@
New features since last release
+* Rectangular GKP states are now supported.
+ [(#668)](https://github.com/XanaduAI/strawberryfields/pull/668)
+
+ For example,
+
+ ```python
+ prog = sf.Program(1)
+
+ with prog.context as q:
+ sf.ops.GKP(shape="rectangular", alpha=2) | q[0]
+ ```
+
Breaking Changes
Bug fixes
@@ -12,6 +24,8 @@
This release contains contributions from (in alphabetical order):
+J. Eli Bourassa
+
# Release 0.21.0 (current release)
New features since last release
diff --git a/tests/backend/test_bosonic_backend.py b/tests/backend/test_bosonic_backend.py
index 3031ffe64..1071e24a5 100644
--- a/tests/backend/test_bosonic_backend.py
+++ b/tests/backend/test_bosonic_backend.py
@@ -473,7 +473,7 @@ def test_gkp_complex(self):
backend = bosonic.BosonicBackend()
with pytest.raises(NotImplementedError):
backend.run_prog(prog)
-
+
@pytest.mark.parametrize("eps", EPS_VALS)
def test_sensor_gkp(self, eps):
r"""Checks that the GKP sensor state is invariant under Fourier."""
@@ -483,7 +483,7 @@ def test_sensor_gkp(self, eps):
# Prepare GKP 0 and apply Hadamard
prog_sensor = sf.Program(1)
with prog_sensor.context as q:
- sf.ops.GKP(state=[np.pi/2,0], epsilon=eps, shape="rectangular", alpha=2) | q[0]
+ sf.ops.GKP(state=[np.pi / 2, 0], epsilon=eps, shape="rectangular", alpha=2) | q[0]
backend_sensor = bosonic.BosonicBackend()
backend_sensor.run_prog(prog_sensor)
@@ -493,7 +493,7 @@ def test_sensor_gkp(self, eps):
# Prepare GKP +
prog_sensor_F = sf.Program(1)
with prog_sensor_F.context as qF:
- sf.ops.GKP(state=[np.pi/2,0], epsilon=eps, shape="rectangular", alpha=2) | qF[0]
+ sf.ops.GKP(state=[np.pi / 2, 0], epsilon=eps, shape="rectangular", alpha=2) | qF[0]
sf.ops.Rgate(np.pi / 2) | qF[0]
backend_sensor_F = bosonic.BosonicBackend()
@@ -529,9 +529,9 @@ def test_gkp_wigner_compare_backends(self, fock_eps):
gkp_bosonic = eng_bosonic.run(prog_bosonic).state
W_bosonic = gkp_bosonic.wigner(0, xvec, xvec)
assert np.allclose(W_fock, W_bosonic)
-
- @pytest.mark.parametrize("fock_eps", [0.1,0.2,0.3])
- @pytest.mark.parametrize("rect_ratio", [0.8,1,1.5])
+
+ @pytest.mark.parametrize("fock_eps", [0.1, 0.2, 0.3])
+ @pytest.mark.parametrize("rect_ratio", [0.8, 1, 1.5])
def test_rect_gkp_wigner_compare_backends(self, fock_eps, rect_ratio):
"""Test correct Wigner function are generated by comparing fock and bosonic outputs.
Since the fock backend cannot simulate very small epsilon, we restrict to fock_eps>0.1."""
From 7d7ee100d270fdfe4eb96642d62a200f4c87eea4 Mon Sep 17 00:00:00 2001
From: elib20 <53090166+elib20@users.noreply.github.com>
Date: Fri, 17 Dec 2021 18:47:52 -0500
Subject: [PATCH 4/9] Update test_ops_gate.py
---
tests/frontend/test_ops_gate.py | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/tests/frontend/test_ops_gate.py b/tests/frontend/test_ops_gate.py
index 422e8fd9b..3b2b5b1ee 100644
--- a/tests/frontend/test_ops_gate.py
+++ b/tests/frontend/test_ops_gate.py
@@ -174,12 +174,13 @@ class TestGKPBasics:
@pytest.mark.parametrize("ampl", [0, 0.001])
@pytest.mark.parametrize("eps", [0, 0.001])
@pytest.mark.parametrize("r", ["real", "complex"])
- @pytest.mark.parametrize("s", ["square"])
- def test_gkp_str_representation(self, state, ampl, eps, r, s):
+ @pytest.mark.parametrize("s", ["square", "rectangular"])
+ @pytest.mark.parametrize("alph", [0.8,1.1])
+ def test_gkp_str_representation(self, state, ampl, eps, r, s, alph):
"""Test the string representation of the GKP operation"""
assert (
- str(ops.GKP(state=state, ampl_cutoff=ampl, epsilon=eps, representation=r, shape=s))
- == f"GKP({str(state)}, {str(eps)}, {str(ampl)}, {r}, {s})"
+ str(ops.GKP(state=state, ampl_cutoff=ampl, epsilon=eps, representation=r, shape=s, alpha=alph))
+ == f"GKP({str(state)}, {str(eps)}, {str(ampl)}, {r}, {s}, {str(alph)})"
)
From 4ffa167700a03b1a148f21c303287ea6edfa0675 Mon Sep 17 00:00:00 2001
From: elib20 <53090166+elib20@users.noreply.github.com>
Date: Fri, 17 Dec 2021 18:50:57 -0500
Subject: [PATCH 5/9] Ran black
---
tests/frontend/test_ops_gate.py | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/tests/frontend/test_ops_gate.py b/tests/frontend/test_ops_gate.py
index 3b2b5b1ee..99a4872dd 100644
--- a/tests/frontend/test_ops_gate.py
+++ b/tests/frontend/test_ops_gate.py
@@ -175,11 +175,20 @@ class TestGKPBasics:
@pytest.mark.parametrize("eps", [0, 0.001])
@pytest.mark.parametrize("r", ["real", "complex"])
@pytest.mark.parametrize("s", ["square", "rectangular"])
- @pytest.mark.parametrize("alph", [0.8,1.1])
+ @pytest.mark.parametrize("alph", [0.8, 1.1])
def test_gkp_str_representation(self, state, ampl, eps, r, s, alph):
"""Test the string representation of the GKP operation"""
assert (
- str(ops.GKP(state=state, ampl_cutoff=ampl, epsilon=eps, representation=r, shape=s, alpha=alph))
+ str(
+ ops.GKP(
+ state=state,
+ ampl_cutoff=ampl,
+ epsilon=eps,
+ representation=r,
+ shape=s,
+ alpha=alph,
+ )
+ )
== f"GKP({str(state)}, {str(eps)}, {str(ampl)}, {r}, {s}, {str(alph)})"
)
From 831e2811676a35f2aaa27f9e99c21b8f317ecc56 Mon Sep 17 00:00:00 2001
From: elib20 <53090166+elib20@users.noreply.github.com>
Date: Tue, 21 Dec 2021 16:45:07 -0500
Subject: [PATCH 6/9] Minor changes based on Ilan's review
Co-Authored-By: ilan-tz <57886357+ilan-tz@users.noreply.github.com>
---
strawberryfields/backends/bosonicbackend/backend.py | 7 ++++---
strawberryfields/backends/fockbackend/backend.py | 2 +-
strawberryfields/backends/fockbackend/circuit.py | 6 +++---
strawberryfields/backends/fockbackend/ops.py | 8 ++++----
strawberryfields/ops.py | 2 +-
5 files changed, 13 insertions(+), 12 deletions(-)
diff --git a/strawberryfields/backends/bosonicbackend/backend.py b/strawberryfields/backends/bosonicbackend/backend.py
index ebea78ee8..f5a20983c 100644
--- a/strawberryfields/backends/bosonicbackend/backend.py
+++ b/strawberryfields/backends/bosonicbackend/backend.py
@@ -557,7 +557,7 @@ def prepare_gkp(
ampl_cutoff (float): this determines how many terms to keep
representation (str): ``'real'`` or ``'complex'`` reprsentation
shape (str): shape of the lattice; default 'square'
- alpha (float): peak spacing in q is given by sqrt(alpha * pi)
+ alpha (float): peak spacing in q is given by sqrt(alpha * pi * hbar)
Returns:
tuple: arrays of the weights, means and covariances for the state
@@ -586,6 +586,7 @@ def coeff(peak_loc, alpha):
Args:
peak_loc (array): location of the ideal peak in phase space
+ alpha (float): peak spacing in q is given by sqrt(alpha * pi * hbar)
Returns:
float: weight of the peak
@@ -620,7 +621,7 @@ def coeff(peak_loc, alpha):
prefactor = np.exp(
-np.pi
* 0.25
- * ((l * alpha) ** 2 + (m / alpha) ** 2)
+ * ((l * np.sqrt(alpha)) ** 2 + (m / np.sqrt(alpha)) ** 2)
* (1 - np.exp(-2 * epsilon))
/ (1 + np.exp(-2 * epsilon))
)
@@ -659,7 +660,7 @@ def coeff(peak_loc, alpha):
)
# Calculate the weights for each peak
- weights = coeff(means, np.sqrt(alpha))
+ weights = coeff(means, alpha)
filt = abs(weights) > ampl_cutoff
weights = weights[filt]
diff --git a/strawberryfields/backends/fockbackend/backend.py b/strawberryfields/backends/fockbackend/backend.py
index bb3d3dc0b..71d64da72 100644
--- a/strawberryfields/backends/fockbackend/backend.py
+++ b/strawberryfields/backends/fockbackend/backend.py
@@ -311,7 +311,7 @@ def prepare_gkp(
amplcutoff (float): this determines how many terms to keep
representation (str): ``'real'`` or ``'complex'`` reprsentation
shape (str): shape of the lattice; default 'square'
- alpha (float): peak spacing in q is given by sqrt(alpha * pi)
+ alpha (float): peak spacing in q is given by sqrt(alpha * pi * hbar)
Returns:
tuple: arrays of the weights, means and covariances for the state
diff --git a/strawberryfields/backends/fockbackend/circuit.py b/strawberryfields/backends/fockbackend/circuit.py
index e27c33e9e..b5962b5ae 100644
--- a/strawberryfields/backends/fockbackend/circuit.py
+++ b/strawberryfields/backends/fockbackend/circuit.py
@@ -799,15 +799,15 @@ def measure_homodyne(self, phi, mode, select=None, **kwargs):
# `homodyne_sample` will always be a single value since multiple shots is not supported
return np.array([[homodyne_sample]])
- def prepare_gkp(self, theta, phi, epsilon, alpha, ampl_cutoff, mode):
+ def prepare_gkp(self, theta, phi, epsilon, ampl_cutoff, alpha, mode):
"""
Prepares a mode in a GKP state.
"""
if self._pure:
self.prepare(
- ops.rect_gkp_state(theta, phi, epsilon, alpha, ampl_cutoff, self._trunc), mode
+ ops.rect_gkp_state(theta, phi, epsilon, ampl_cutoff, alpha, self._trunc), mode
)
else:
- st = ops.rect_gkp_state(theta, phi, epsilon, alpha, ampl_cutoff, self._trunc)
+ st = ops.rect_gkp_state(theta, phi, epsilon, ampl_cutoff, alpha, self._trunc)
self.prepare(np.outer(st, st.conjugate()), mode)
diff --git a/strawberryfields/backends/fockbackend/ops.py b/strawberryfields/backends/fockbackend/ops.py
index 0d20853d8..9d004bb52 100644
--- a/strawberryfields/backends/fockbackend/ops.py
+++ b/strawberryfields/backends/fockbackend/ops.py
@@ -524,7 +524,7 @@ def gkp_displacements(t, k, epsilon, alpha):
t (array): the teeth of GKP computational basis
k (int): a computational basis state label, can be either 0 or 1
epsilon (float): finite energy parameter of the state
- alpha (float): peak spacing in q is given by sqrt(alpha * pi)
+ alpha (float): peak spacing in q is given by sqrt(alpha * pi * hbar)
Returns:
array: the displacements
@@ -541,7 +541,7 @@ def gkp_coeffs(t, k, epsilon, alpha):
t (array): the teeth of GKP computational basis
k (int): a computational basis state label, can be either 0 or 1
epsilon (float): finite energy parameter of the state
- alpha (float): peak spacing in q is given by sqrt(alpha * pi)
+ alpha (float): peak spacing in q is given by sqrt(alpha * pi * hbar)
Returns:
array: the coefficients
@@ -558,7 +558,7 @@ def rect_gkp_basis_state(i, epsilon, ampl_cutoff, alpha, cutoff):
i (int): a computational basis state label, can be either 0 or 1
epsilon (float): finite energy parameter of the state
ampl_cutoff (float): this determines how many terms to keep in the Hilbert space expansion
- alpha (float): peak spacing in q is given by sqrt(alpha * pi)
+ alpha (float): peak spacing in q is given by sqrt(alpha * pi * hbar)
cutoff (int): Fock space truncation
Returns
@@ -585,7 +585,7 @@ def rect_gkp_state(theta, phi, epsilon, ampl_cutoff, alpha, cutoff):
phi (float): the longitude with respect to the x-axis in the Bloch sphere
epsilon (float): finite energy parameter of the state
ampl_cutoff (float): this determines how many terms to keep
- alpha (float): peak spacing in q is given by sqrt(alpha * pi)
+ alpha (float): peak spacing in q is given by sqrt(alpha * pi * hbar)
cutoff (int): Fock space truncation
Returns:
diff --git a/strawberryfields/ops.py b/strawberryfields/ops.py
index 95a8d7824..8d8389cab 100644
--- a/strawberryfields/ops.py
+++ b/strawberryfields/ops.py
@@ -949,7 +949,7 @@ class GKP(Preparation):
cutoff (float): this determines how many terms to keep
representation (str): ``'real'`` or ``'complex'`` reprsentation
shape (str): shape of the lattice; default ``'square'``
- alpha (float): peak spacing in q is given by sqrt(alpha * pi)
+ alpha (float): peak spacing in q is given by sqrt(alpha * pi * hbar)
"""
def __init__(
From ce277807f3957e2d6b61eb95d4a069ff9c287425 Mon Sep 17 00:00:00 2001
From: elib20 <53090166+elib20@users.noreply.github.com>
Date: Tue, 21 Dec 2021 16:46:31 -0500
Subject: [PATCH 7/9] Apply suggestions from code review
---
strawberryfields/backends/bosonicbackend/backend.py | 2 +-
strawberryfields/backends/fockbackend/backend.py | 2 +-
tests/backend/test_bosonic_backend.py | 6 +++---
3 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/strawberryfields/backends/bosonicbackend/backend.py b/strawberryfields/backends/bosonicbackend/backend.py
index f5a20983c..d4392896f 100644
--- a/strawberryfields/backends/bosonicbackend/backend.py
+++ b/strawberryfields/backends/bosonicbackend/backend.py
@@ -576,7 +576,7 @@ def prepare_gkp(
if alpha != 1:
raise ValueError(
"For square GKPs, alpha must be 1. For alpha not equal to "
- + "1, use shape='rectangular'."
+ + "1, use shape=\"rectangular\"."
)
theta, phi = state[0], state[1]
diff --git a/strawberryfields/backends/fockbackend/backend.py b/strawberryfields/backends/fockbackend/backend.py
index 71d64da72..7df10aa9d 100644
--- a/strawberryfields/backends/fockbackend/backend.py
+++ b/strawberryfields/backends/fockbackend/backend.py
@@ -330,7 +330,7 @@ def prepare_gkp(
if alpha != 1:
raise ValueError(
"For square GKPs, alpha must be 1. For alpha not equal to "
- + "1, use shape='rectangular'."
+ + "1, use shape=\"rectangular\"."
)
theta, phi = state[0], state[1]
diff --git a/tests/backend/test_bosonic_backend.py b/tests/backend/test_bosonic_backend.py
index 1071e24a5..b46abc716 100644
--- a/tests/backend/test_bosonic_backend.py
+++ b/tests/backend/test_bosonic_backend.py
@@ -476,7 +476,7 @@ def test_gkp_complex(self):
@pytest.mark.parametrize("eps", EPS_VALS)
def test_sensor_gkp(self, eps):
- r"""Checks that the GKP sensor state is invariant under Fourier."""
+ r"""Checks that the GKP sensor state is invariant under Fourier gate."""
x = np.linspace(-3 * np.sqrt(np.pi), 3 * np.sqrt(np.pi), 40)
p = np.copy(x)
@@ -533,8 +533,8 @@ def test_gkp_wigner_compare_backends(self, fock_eps):
@pytest.mark.parametrize("fock_eps", [0.1, 0.2, 0.3])
@pytest.mark.parametrize("rect_ratio", [0.8, 1, 1.5])
def test_rect_gkp_wigner_compare_backends(self, fock_eps, rect_ratio):
- """Test correct Wigner function are generated by comparing fock and bosonic outputs.
- Since the fock backend cannot simulate very small epsilon, we restrict to fock_eps>0.1."""
+ """Test that correct Wigner function is generated by comparing fock and bosonic outputs.
+ Since the fock backend cannot simulate very small epsilon, we restrict to fock_eps > 0.1."""
theta = np.pi / 8
phi = np.pi / 6
ket = [theta, phi]
From 60a88803e95a7b0243c0011d3793c0ebf124efd2 Mon Sep 17 00:00:00 2001
From: elib20 <53090166+elib20@users.noreply.github.com>
Date: Tue, 21 Dec 2021 16:51:13 -0500
Subject: [PATCH 8/9] Ran black
---
strawberryfields/backends/bosonicbackend/backend.py | 2 +-
strawberryfields/backends/fockbackend/backend.py | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/strawberryfields/backends/bosonicbackend/backend.py b/strawberryfields/backends/bosonicbackend/backend.py
index d4392896f..77b7c412d 100644
--- a/strawberryfields/backends/bosonicbackend/backend.py
+++ b/strawberryfields/backends/bosonicbackend/backend.py
@@ -576,7 +576,7 @@ def prepare_gkp(
if alpha != 1:
raise ValueError(
"For square GKPs, alpha must be 1. For alpha not equal to "
- + "1, use shape=\"rectangular\"."
+ + '1, use shape="rectangular".'
)
theta, phi = state[0], state[1]
diff --git a/strawberryfields/backends/fockbackend/backend.py b/strawberryfields/backends/fockbackend/backend.py
index 7df10aa9d..4a99f6861 100644
--- a/strawberryfields/backends/fockbackend/backend.py
+++ b/strawberryfields/backends/fockbackend/backend.py
@@ -330,7 +330,7 @@ def prepare_gkp(
if alpha != 1:
raise ValueError(
"For square GKPs, alpha must be 1. For alpha not equal to "
- + "1, use shape=\"rectangular\"."
+ + '1, use shape="rectangular".'
)
theta, phi = state[0], state[1]
From 0d6c810e40000784c5d82d057165cdfdac6a6936 Mon Sep 17 00:00:00 2001
From: elib20 <53090166+elib20@users.noreply.github.com>
Date: Wed, 22 Dec 2021 08:53:09 -0500
Subject: [PATCH 9/9] Apply suggestions from code review
---
strawberryfields/backends/bosonicbackend/backend.py | 2 +-
strawberryfields/backends/fockbackend/backend.py | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/strawberryfields/backends/bosonicbackend/backend.py b/strawberryfields/backends/bosonicbackend/backend.py
index 77b7c412d..f5a20983c 100644
--- a/strawberryfields/backends/bosonicbackend/backend.py
+++ b/strawberryfields/backends/bosonicbackend/backend.py
@@ -576,7 +576,7 @@ def prepare_gkp(
if alpha != 1:
raise ValueError(
"For square GKPs, alpha must be 1. For alpha not equal to "
- + '1, use shape="rectangular".'
+ + "1, use shape='rectangular'."
)
theta, phi = state[0], state[1]
diff --git a/strawberryfields/backends/fockbackend/backend.py b/strawberryfields/backends/fockbackend/backend.py
index 4a99f6861..71d64da72 100644
--- a/strawberryfields/backends/fockbackend/backend.py
+++ b/strawberryfields/backends/fockbackend/backend.py
@@ -330,7 +330,7 @@ def prepare_gkp(
if alpha != 1:
raise ValueError(
"For square GKPs, alpha must be 1. For alpha not equal to "
- + '1, use shape="rectangular".'
+ + "1, use shape='rectangular'."
)
theta, phi = state[0], state[1]