states

Module for representing quantum states.

The BaseState-class is intended to be subclassed for different types of states, e.g. qubit states, qudit states, fock states etc.

The State-class is then a sum of BaseState-class in the sum.

class qualg.states.BaseState

Abstract base state class. Represents a single term of state and used to define how inner product should be taken etc.

Meant to be subclassed.

abstract inner_product(other)

Takes the inner product with another BaseState.

Parameters

other (BaseState) – The right hand side of the inner product.

Returns

The inner product

Return type

class`~.scalar.Scalar`

abstract tensor_product(other)

Takes the tensor product with another BaseState.

Parameters

other (BaseState) – The right hand side of the tensor product.

Returns

The tensor product

Return type

BaseState

to_state()

Converts the base state to a state with a single term.

property shape

Returns the shape of the state, e.q. (2,) for a qubit.

None means that the shape is undefined, e.g. if the state is infinite-dimensional.

class qualg.states.State(base_states=None, scalars=None)

__init__(base_states=None, scalars=None)

A quantum state. Constructed as a sum of (subclass) BaseState.

Parameters

• base_states (None or list of BaseState) – The base states that sums up to this state. If None, then the state is “zero”, i.e. no terms.

• scalar (None or list of Scalar) – The amplitudes used when taking the sum of base states. If None, then all operators have amplitude 1.

get_scalar(base_state)

Returns the scalar of the given base_state

inner_product(other, first_replace_var=True)

Takes the inner product with another State.

Parameters

• other (State) – The right hand side of the inner product.

• (optional) (first_replace_var) – Whether to replace all varibles of the right hand side with new ones (only done for SingleVarFunctionScalar). This can be useful when the two states are actually integrals over the variables and should therefore be different.

Returns

The inner product

Return type

class`~.scalar.Scalar`

tensor_product(other)

Takes the tensor product with another State.

Parameters

other (State) – The right hand side of the tensor product.

Returns

The tensor product

Return type

State

simplify()

Tries to simplify the state.

replace_var(old_variable, new_variable)

Replaces a variable with another.

get_variables()

Returns the variable of this operator.