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# HamiltonianGate

class qiskit.extensions.HamiltonianGate(data, time, label=None)

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Bases: Gate

Class for representing evolution by a Hamiltonian operator as a gate.

This gate resolves to a UnitaryGate as $U(t) = exp(-i t H)$, which can be decomposed into basis gates if it is 2 qubits or less, or simulated directly in Aer for more qubits. Note that you can also directly use QuantumCircuit.hamiltonian().

Create a gate from a hamiltonian operator and evolution time parameter t

Parameters

• data (matrix or Operator) – a hermitian operator.
• time (float orParameterExpression) – time evolution parameter.
• label (str) – unitary name for backend [Default: None].

Raises

ExtensionError – if input data is not an N-qubit unitary operator.

## Attributes

### condition_bits

Get Clbits in condition.

### decompositions

Get the decompositions of the instruction from the SessionEquivalenceLibrary.

### definition

Return definition in terms of other basic gates.

### duration

Get the duration.

### label

Return instruction label

Return the name.

### num_clbits

Return the number of clbits.

### num_qubits

Return the number of qubits.

### params

return instruction params.

### unit

Get the time unit of duration.

## Methods

add_decomposition(decomposition)

Add a decomposition of the instruction to the SessionEquivalenceLibrary.

adjoint()

Return the adjoint of the unitary.

### assemble

assemble()

Assemble a QasmQobjInstruction

broadcast_arguments(qargs, cargs)

Validation and handling of the arguments and its relationship.

For example, cx([q[0],q[1]], q[2]) means cx(q[0], q[2]); cx(q[1], q[2]). This method yields the arguments in the right grouping. In the given example:

in: [[q[0],q[1]], q[2]],[]
outs: [q[0], q[2]], []
[q[1], q[2]], []

• If len(qargs) == 1:

[q[0], q[1]] -> [q[0]],[q[1]]
• If len(qargs) == 2:

[[q[0], q[1]], [r[0], r[1]]] -> [q[0], r[0]], [q[1], r[1]]
[[q[0]], [r[0], r[1]]]       -> [q[0], r[0]], [q[0], r[1]]
[[q[0], q[1]], [r[0]]]       -> [q[0], r[0]], [q[1], r[0]]
• If len(qargs) >= 3:

[q[0], q[1]], [r[0], r[1]],  ...] -> [q[0], r[0], ...], [q[1], r[1], ...]

Parameters

• qargs (list) – List of quantum bit arguments.
• cargs (list) – List of classical bit arguments.

Returns

A tuple with single arguments.

Raises

CircuitError – If the input is not valid. For example, the number of arguments does not match the gate expectation.

Return type

### c_if

c_if(classical, val)

Set a classical equality condition on this instruction between the register or cbit classical and value val.

Note

This is a setter method, not an additive one. Calling this multiple times will silently override any previously set condition; it does not stack.

### conjugate

conjugate()

Return the conjugate of the Hamiltonian.

### control

control(num_ctrl_qubits=1, label=None, ctrl_state=None)

Return controlled version of gate. See ControlledGate for usage.

Parameters

• num_ctrl_qubits (int) – number of controls to add to gate (default: 1)
• label (str | None) – optional gate label
• ctrl_state (int |str | None) – The control state in decimal or as a bitstring (e.g. '111'). If None, use 2**num_ctrl_qubits-1.

Returns

Controlled version of gate. This default algorithm uses num_ctrl_qubits-1 ancilla qubits so returns a gate of size num_qubits + 2*num_ctrl_qubits - 1.

Return type

qiskit.circuit.ControlledGate

Raises

QiskitError – unrecognized mode or invalid ctrl_state

### copy

copy(name=None)

Copy of the instruction.

Parameters

name (str) – name to be given to the copied circuit, if None then the name stays the same.

Returns

a copy of the current instruction, with the name updated if it was provided

Return type

qiskit.circuit.Instruction

### inverse

inverse()

Return the adjoint of the unitary.

### is_parameterized

is_parameterized()

Return True .IFF. instruction is parameterized else False

### power

power(exponent)

Creates a unitary gate as gate^exponent.

Parameters

exponent (float) – Gate^exponent

Returns

To which to_matrix is self.to_matrix^exponent.

Return type

qiskit.extensions.UnitaryGate

Raises

CircuitError – If Gate is not unitary

### qasm

qasm()

Raise an error, as QASM is not defined for the HamiltonianGate.

Deprecated since version 0.25.0

The method qiskit.extensions.hamiltonian_gate.HamiltonianGate.qasm() is deprecated as of qiskit-terra 0.25.0. It will be removed no earlier than 3 months after the release date.

### repeat

repeat(n)

Creates an instruction with gate repeated n amount of times.

Parameters

n (int) – Number of times to repeat the instruction

Returns

Containing the definition.

Return type

qiskit.circuit.Instruction

Raises

CircuitError – If n < 1.

### reverse_ops

reverse_ops()

For a composite instruction, reverse the order of sub-instructions.

This is done by recursively reversing all sub-instructions. It does not invert any gate.

Returns

a new instruction with

sub-instructions reversed.

Return type

qiskit.circuit.Instruction

### soft_compare

soft_compare(other)

Soft comparison between gates. Their names, number of qubits, and classical bit numbers must match. The number of parameters must match. Each parameter is compared. If one is a ParameterExpression then it is not taken into account.

Parameters

other (instruction) – other instruction.

Returns

are self and other equal up to parameter expressions.

Return type

bool

### to_matrix

to_matrix()

Return a Numpy.array for the gate unitary matrix.

Returns

if the Gate subclass has a matrix definition.

Return type

np.ndarray

Raises

CircuitError – If a Gate subclass does not implement this method an exception will be raised when this base class method is called.

### transpose

transpose()

Return the transpose of the Hamiltonian.

### validate_parameter

validate_parameter(parameter)

Hamiltonian parameter has to be an ndarray, operator or float.