qml

This is the top level module from which all basic functions and classes of PennyLane can be directly imported.

Functions

about()	Prints the information for pennylane installation.
adjoint(fn)	Create a function that applies the adjoint (inverse) of the provided operation or template.
adjoint_metric_tensor(circuit[, device, hybrid])	Implements the adjoint method outlined in Jones to compute the metric tensor.
apply(op[, context])	Apply an instantiated operator or measurement to a queuing context.
apply_controlled_Q(fn, wires, target_wire, …)	Provides the circuit to apply a controlled version of the \(\mathcal{Q}\) unitary defined in this paper.
batch_params(tape[, all_operations])	Transform a QNode to support an initial batch dimension for operation parameters.
broadcast(unitary, wires, pattern[, …])	Applies a unitary multiple times to a specific pattern of wires.
compile	Compile a circuit by applying a series of transforms to a quantum function.
ctrl(fn, control)	Create a method that applies a controlled version of the provided method.
density_matrix(wires)	Quantum density matrix in the computational basis.
device(name[, wires])	Load a Device and return the instance.
dot(x, y)	Lazily perform the dot product between arrays, tensors, and QNodeCollection.
draw(qnode[, charset, wire_order, …])	Create a function that draws the given qnode.
draw_mpl(qnode[, wire_order, …])	Draw a qnode with matplotlib
execute(tapes, device, gradient_fn[, …])	Execute a batch of tapes on a device in an autodifferentiable-compatible manner.
expval(op)	Expectation value of the supplied observable.
finite_diff(f[, N, argnum, idx, delta])	Returns a function that can be evaluated to compute the gradient or the second-order derivative of the callable function f using a centered finite difference approximation.
from_pyquil(pyquil_program)	Loads pyQuil Program objects by using the converter in the PennyLane-Forest plugin.
from_qasm(quantum_circuit)	Loads quantum circuits from a QASM string using the converter in the PennyLane-Qiskit plugin.
from_qasm_file(qasm_filename)	Loads quantum circuits from a QASM file using the converter in the PennyLane-Qiskit plugin.
from_qiskit(quantum_circuit)	Loads Qiskit QuantumCircuit objects by using the converter in the PennyLane-Qiskit plugin.
from_quil(quil)	Loads quantum circuits from a Quil string using the converter in the PennyLane-Forest plugin.
from_quil_file(quil_filename)	Loads quantum circuits from a Quil file using the converter in the PennyLane-Forest plugin.
jacobian(func[, argnum])	Returns the Jacobian as a callable function of vector-valued (functions of) QNodes.
layer(template, depth, *args, **kwargs)	Repeatedly applies a unitary a given number of times.
load(quantum_circuit_object, format)	Load external quantum assembly and quantum circuits from supported frameworks into PennyLane templates.
map(template, observables, device[, …])	Map a quantum template over a list of observables to create a QNodeCollection.
measurement_grouping(tape, obs_list, coeffs_list)	Returns a list of measurement optimized tapes, and a classical processing function, for evaluating the expectation value of a provided Hamiltonian.
metric_tensor(tape[, approx, …])	Returns a function that computes the metric tensor of a given QNode or quantum tape.
probs([wires, op])	Probability of each computational basis state.
qfunc_transform(tape_transform)	Given a function which defines a tape transform, convert the function into one that applies the tape transform to quantum functions (qfuncs).
qnode(func, device[, interface, …])	Represents a quantum node in the hybrid computational graph.
quantum_monte_carlo(fn, wires, target_wire, …)	Provides the circuit to perform the quantum Monte Carlo estimation algorithm.
refresh_devices()	Scan installed PennyLane plugins to refresh the device list.
sample([op, wires])	Sample from the supplied observable, with the number of shots determined from the dev.shots attribute of the corresponding device.
specs(qnode[, max_expansion])	Resource information about a quantum circuit.
state()	Quantum state in the computational basis.
sum(x)	Lazily sum the constituent QNodes of a QNodeCollection.
var(op)	Variance of the supplied observable.
version()	Returns the PennyLane version number.

Classes

AdagradOptimizer([stepsize, eps])	Gradient-descent optimizer with past-gradient-dependent learning rate in each dimension.
AdamOptimizer([stepsize, beta1, beta2, eps])	Gradient-descent optimizer with adaptive learning rate, first and second moment.
AllSinglesDoubles(weights, wires, hf_state)	Builds a quantum circuit to prepare correlated states of molecules by applying all SingleExcitation and DoubleExcitation operations to the initial Hartree-Fock state.
AmplitudeDamping(gamma, wires)	Single-qubit amplitude damping error channel.
AmplitudeEmbedding(features, wires[, …])	Encodes \(2^n\) features into the amplitude vector of \(n\) qubits.
AngleEmbedding(features, wires[, rotation, …])	Encodes \(N\) features into the rotation angles of \(n\) qubits, where \(N \leq n\).
ApproxTimeEvolution(hamiltonian, time, n[, …])	Applies the Trotterized time-evolution operator for an arbitrary Hamiltonian, expressed in terms of Pauli gates.
ArbitraryStatePreparation(weights, wires[, …])	Implements an arbitrary state preparation on the specified wires.
ArbitraryUnitary(weights, wires[, do_queue, id])	Implements an arbitrary unitary on the specified wires.
Barrier(wires)	The Barrier operator, used to separate the compilation process into blocks or as a visual tool.
BasicEntanglerLayers(weights[, wires, …])	Layers consisting of one-parameter single-qubit rotations on each qubit, followed by a closed chain or ring of CNOT gates.
BasisEmbedding(features, wires[, do_queue, id])	Encodes \(n\) binary features into a basis state of \(n\) qubits.
BasisState(n, wires)	Prepares a single computational basis state.
BasisStatePreparation(basis_state, wires[, …])	Prepares a basis state on the given wires using a sequence of Pauli-X gates.
Beamsplitter(theta, phi, wires)	Beamsplitter interaction.
BitFlip(p, wires)	Single-qubit bit flip (Pauli \(X\)) error channel.
BooleanFn(fn)	Wrapper for simple callables with boolean output that can be manipulated and combined with bit-wise operators.
CNOT(wires)	The controlled-NOT operator
CPhase	alias of pennylane.ops.qubit.parametric_ops.ControlledPhaseShift
CRX(phi, wires)	The controlled-RX operator
CRY(phi, wires)	The controlled-RY operator
CRZ(phi, wires)	The controlled-RZ operator
CRot(phi, theta, omega, wires)	The controlled-Rot operator
CSWAP(wires)	The controlled-swap operator
CVNeuralNetLayers(theta_1, phi_1, varphi_1, …)	A sequence of layers of a continuous-variable quantum neural network, as specified in arXiv:1806.06871.
CY(wires)	The controlled-Y operator
CZ(wires)	The controlled-Z operator
CatState(a, phi, p, wires)	Prepares a cat state.
CircuitGraph(ops, obs, wires[, par_info, …])	Represents a quantum circuit as a directed acyclic graph.
CoherentState(a, phi, wires)	Prepares a coherent state.
CommutingEvolution(hamiltonian, time[, …])	Applies the time-evolution operator for a Hamiltonian expressed as a linear combination of mutually commuting Pauli words.
Configuration(name)	Configuration class.
ControlledAddition(s, wires)	Controlled addition operation.
ControlledOperation(tape, control_wires[, …])	A Controlled Operation.
ControlledPhase(s, wires)	Controlled phase operation.
ControlledPhaseShift(phi, wires)	A qubit controlled phase shift.
ControlledQubitUnitary(U, control_wires, …)	Apply an arbitrary fixed unitary to wires with control from the control_wires.
CrossKerr(kappa, wires)	Cross-Kerr interaction.
CubicPhase(gamma, wires)	Cubic phase shift.
DepolarizingChannel(p, wires)	Single-qubit symmetrically depolarizing error channel.
Device([wires, shots, analytic])	Abstract base class for PennyLane devices.
DeviceError	Exception raised by a Device when it encounters an illegal operation in the quantum circuit.
DiagonalQubitUnitary(D, wires)	Apply an arbitrary fixed diagonal unitary matrix.
DisplacedSqueezedState(a, phi_a, r, phi_r, wires)	Prepares a displaced squeezed vacuum state.
Displacement(a, phi, wires)	Phase space displacement.
DisplacementEmbedding(features, wires[, …])	Encodes \(N\) features into the displacement amplitudes \(r\) or phases \(\phi\) of \(M\) modes, where \(N\leq M\).
DoubleExcitation(phi, wires)	Double excitation rotation.
DoubleExcitationMinus(phi, wires)	Double excitation rotation with negative phase-shift outside the rotation subspace.
DoubleExcitationPlus(phi, wires)	Double excitation rotation with positive phase-shift outside the rotation subspace.
ExpvalCost(ansatz, hamiltonian, device[, …])	Create a cost function that gives the expectation value of an input Hamiltonian.
FermionicDoubleExcitation(weight[, wires1, …])	Circuit to exponentiate the tensor product of Pauli matrices representing the double-excitation operator entering the Unitary Coupled-Cluster Singles and Doubles (UCCSD) ansatz.
FermionicSingleExcitation(weight[, wires, …])	Circuit to exponentiate the tensor product of Pauli matrices representing the single-excitation operator entering the Unitary Coupled-Cluster Singles and Doubles (UCCSD) ansatz.
FockDensityMatrix(state, wires)	Prepare subsystems using the given density matrix in the Fock basis.
FockState(n, wires)	Prepares a single Fock state.
FockStateProjector(n, wires)	The number state observable \(\ket{n}\bra{n}\).
FockStateVector(state, wires)	Prepare subsystems using the given ket vector in the Fock basis.
GateFabric(weights, wires, init_state[, …])	Implements a local, expressive, and quantum-number-preserving ansatz proposed by Anselmetti et al. in arXiv:2104.05692.
GaussianState(V, r, wires)	Prepare subsystems in a given Gaussian state.
GeneralizedAmplitudeDamping(gamma, p, wires)	Single-qubit generalized amplitude damping error channel.
GradientDescentOptimizer([stepsize])	Basic gradient-descent optimizer.
GroverOperator([wires, work_wires, do_queue, id])	Performs the Grover Diffusion Operator.
Hadamard(wires)	The Hadamard operator
Hamiltonian(coeffs, observables[, simplify, …])	Operator representing a Hamiltonian.
Hermitian(A, wires)	An arbitrary Hermitian observable.
IQPEmbedding(features, wires[, n_repeats, …])	Encodes \(n\) features into \(n\) qubits using diagonal gates of an IQP circuit.
ISWAP(wires)	The i-swap operator
Identity(wires)	The identity observable \(\I\).
Interferometer(theta, phi, varphi, wires[, …])	General linear interferometer, an array of beamsplitters and phase shifters.
InterferometerUnitary(U, wires)	A linear interferometer transforming the bosonic operators according to the unitary matrix \(U\).
IsingXX(phi, wires)	Ising XX coupling gate
IsingYY(phi, wires)	Ising YY coupling gate
IsingZZ(phi, wires)	Ising ZZ coupling gate
Kerr(kappa, wires)	Kerr interaction.
LieAlgebraOptimizer(circuit[, stepsize, …])	Lie algebra optimizer.
MPS(wires, n_block_wires, block, n_params_block)	The MPS template broadcasts an input circuit across many wires following the architecture of a Matrix Product State tensor network.
MomentumOptimizer([stepsize, momentum])	Gradient-descent optimizer with momentum.
MottonenStatePreparation(state_vector, wires)	Prepares an arbitrary state on the given wires using a decomposition into gates developed by Möttönen et al. (2004).
MultiControlledX(control_wires, wires, …)	Apply a Pauli X gate controlled on an arbitrary computational basis state.
MultiRZ(theta, wires)	Arbitrary multi Z rotation.
NesterovMomentumOptimizer([stepsize, momentum])	Gradient-descent optimizer with Nesterov momentum.
NumberOperator(wires)	The photon number observable \(\langle \hat{n}\rangle\).
OrbitalRotation(phi, wires)	Spin-adapted spatial orbital rotation.
P(wires)	The momentum quadrature observable \(\hat{p}\).
ParticleConservingU1(weights, wires[, …])	Implements the heuristic VQE ansatz for quantum chemistry simulations using the particle-conserving gate \(U_{1,\mathrm{ex}}\) proposed by Barkoutsos et al. in arXiv:1805.04340.
ParticleConservingU2(weights, wires[, …])	Implements the heuristic VQE ansatz for Quantum Chemistry simulations using the particle-conserving entangler \(U_\mathrm{ent}(\vec{\theta}, \vec{\phi})\) proposed in arXiv:1805.04340.
PauliError(operators, p, wires)	Pauli operator error channel for an arbitrary number of qubits.
PauliRot(theta, pauli_word, wires)	Arbitrary Pauli word rotation.
PauliX(wires)	The Pauli X operator
PauliY(wires)	The Pauli Y operator
PauliZ(wires)	The Pauli Z operator
Permute(permutation, wires[, do_queue, id])	Applies a permutation to a set of wires.
PhaseDamping(gamma, wires)	Single-qubit phase damping error channel.
PhaseFlip(p, wires)	Single-qubit bit flip (Pauli \(Z\)) error channel.
PhaseShift(phi, wires)	Arbitrary single qubit local phase shift
PolyXP(q, wires)	An arbitrary second-order polynomial observable.
Projector(basis_state, wires)	Observable corresponding to the computational basis state projector \(P=\ket{i}\bra{i}\).
QAOAEmbedding(features, weights, wires[, …])	Encodes \(N\) features into \(n>N\) qubits, using a layered, trainable quantum circuit that is inspired by the QAOA ansatz.
QFT(wires)	Apply a quantum Fourier transform (QFT).
QNGOptimizer([stepsize, approx, lam])	Optimizer with adaptive learning rate, via calculation of the diagonal or block-diagonal approximation to the Fubini-Study metric tensor.
QNode(func, device[, interface, …])	Represents a quantum node in the hybrid computational graph.
QNodeCollection([qnodes])	Represents a sequence of independent QNodes that all share the same signature.
QuadOperator(phi, wires)	The generalized quadrature observable \(\x_\phi = \x cos\phi+\p\sin\phi\).
QuadraticPhase(s, wires)	Quadratic phase shift.
QuantumFunctionError	Exception raised when an illegal operation is defined in a quantum function.
QuantumMonteCarlo(probs, func, target_wires, …)	Performs the quantum Monte Carlo estimation algorithm.
QuantumPhaseEstimation(unitary, …[, …])	Performs the quantum phase estimation circuit.
QubitCarry(wires)	Apply the QubitCarry operation to four input wires.
QubitChannel(K_list, wires)	Apply an arbitrary fixed quantum channel.
QubitDensityMatrix(state, wires)	Prepare subsystems using the given density matrix.
QubitDevice([wires, shots, cache, analytic])	Abstract base class for PennyLane qubit devices.
QubitStateVector(state, wires)	Prepare subsystems using the given ket vector in the computational basis.
QubitSum(wires)	Apply a QubitSum operation on three input wires.
QubitUnitary(U, wires)	Apply an arbitrary fixed unitary matrix.
QueuingContext()	Abstract base class for classes that exposes a queue for objects.
RMSPropOptimizer([stepsize, decay, eps])	Root mean squared propagation optimizer.
RX(phi, wires)	The single qubit X rotation
RY(phi, wires)	The single qubit Y rotation
RZ(phi, wires)	The single qubit Z rotation
RandomLayers(weights, wires[, ratio_imprim, …])	Layers of randomly chosen single qubit rotations and 2-qubit entangling gates, acting on randomly chosen qubits.
ResetError(p_0, p_1, wires)	Single-qubit Reset error channel.
Rot(phi, theta, omega, wires)	Arbitrary single qubit rotation
Rotation(phi, wires)	Phase space rotation.
RotoselectOptimizer([possible_generators])	Rotoselect gradient-free optimizer.
RotosolveOptimizer([substep_optimizer, …])	Rotosolve gradient-free optimizer.
S(wires)	The single-qubit phase gate
SISWAP(wires)	The square root of i-swap operator.
SQISW	alias of pennylane.ops.qubit.non_parametric_ops.SISWAP
SWAP(wires)	The swap operator
SX(wires)	The single-qubit Square-Root X operator.
ShotAdaptiveOptimizer(min_shots[, …])	Optimizer where the shot rate is adaptively calculated using the variances of the parameter-shift gradient.
SimplifiedTwoDesign(initial_layer_weights, …)	Layers consisting of a simplified 2-design architecture of Pauli-Y rotations and controlled-Z entanglers proposed in Cerezo et al. (2020).
SingleExcitation(phi, wires)	Single excitation rotation.
SingleExcitationMinus(phi, wires)	Single excitation rotation with negative phase-shift outside the rotation subspace.
SingleExcitationPlus(phi, wires)	Single excitation rotation with positive phase-shift outside the rotation subspace.
SparseHamiltonian(H)	A Hamiltonian represented directly as a sparse matrix in coordinate list (COO) format.
SqueezedState(r, phi, wires)	Prepares a squeezed vacuum state.
Squeezing(r, phi, wires)	Phase space squeezing.
SqueezingEmbedding(features, wires[, …])	Encodes \(N\) features into the squeezing amplitudes \(r \geq 0\) or phases \(\phi \in [0, 2\pi)\) of \(M\) modes, where \(N\leq M\).
StronglyEntanglingLayers(weights, wires[, …])	Layers consisting of single qubit rotations and entanglers, inspired by the circuit-centric classifier design arXiv:1804.00633.
T(wires)	The single-qubit T gate
TTN(wires, n_block_wires, block, n_params_block)	The TTN template broadcasts an input circuit across many wires following the architecture of a tree tensor network.
TensorN(wires)	The tensor product of the NumberOperator acting on different wires.
ThermalRelaxationError(pe, t1, t2, tg, wires)	Thermal relaxation error channel.
ThermalState(nbar, wires)	Prepares a thermal state.
Toffoli(wires)	Toffoli (controlled-controlled-X) gate.
Tracker([dev, callback, persistent])	This class stores information about device executions and allows users to interact with that data upon individual executions and batches, even within parameter-shift gradients and optimization steps.
TwoModeSqueezing(r, phi, wires)	Phase space two-mode squeezing.
U1(phi)	U1 gate.
U2(phi, lambda, wires)	U2 gate.
U3(theta, phi, lambda, wires)	Arbitrary single qubit unitary.
UCCSD(weights, wires[, s_wires, d_wires, …])	Implements the Unitary Coupled-Cluster Singles and Doubles (UCCSD) ansatz.
VQECost(*args, **kwargs)	Create a cost function that gives the expectation value of an input Hamiltonian.
WireCut(wires)	The wire cut operator, used to manually mark locations for wire cuts.
X(wires)	The position quadrature observable \(\hat{x}\).
batch_transform(*args, **kwargs)	Class for registering a tape transform that takes a tape, and outputs a batch of tapes to be independently executed on a quantum device.
grad(fun[, argnum])	Returns the gradient as a callable function of (functions of) QNodes.
kUpCCGSD(weights, wires[, k, delta_sz, …])	Implements the k-Unitary Pair Coupled-Cluster Generalized Singles and Doubles (k-UpCCGSD) ansatz.
single_tape_transform(transform_fn)	For registering a tape transform that takes a tape and outputs a single new tape.

Variables

Class Inheritance Diagram