linopt::Basis Class Reference

The class representing a collection of Fock states. More...

#include <states.h>

Inheritance diagram for linopt::Basis:

Collaboration diagram for linopt::Basis:

Public Types
using	Set = std::set< Fock >
	Convenience typedef to std::set.
using	Value = Fock
using	value_type = Value
using	Reference = Value &
using	reference = Reference
using	Iterator = Base::iterator
using	ConstIterator = Base::const_iterator
using	ReverseIterator = Base::reverse_iterator
using	ConstReverseIterator = Base::const_reverse_iterator

Public Member Functions
int	size () const
	Returns the number of Fock states in the basis.
	Basis (const Set &s)
	Basis (std::initializer_list< Fock > il)
	Basis (int nphot, int modes)
	Constructs a basis of all possible Fock states with modes modes and containing nphot photons.
Basis	operator+ (const Basis &b) const
	Returns a basis which is a union of Fock states from both *this and b.
Basis &	operator+= (const Basis &b)
	Effectively equivalent to *this = (*this) + b.
Basis	operator* (const Basis &b) const
	Calculates a tensor product of two bases. More...
Basis &	operator*= (const Basis &b)
	Effectively equivalent to *this = (*this) * b.
Basis &	generateBasis (const int nphot, const int modes, const Fock &head=Fock())
	Generates a basis of all possible Fock states with modes modes and containing nphot photons. More...
Basis	postselect (const Fock &ancilla) const
	Returns a postselected basis after observing ancilla. More...
template<typename ExecPolicy = execution::Seq>
State	applyFunction (const FockAmpFunction &f) const
	Constructs a state from the basis using function f. More...

Detailed Description

The class representing a collection of Fock states.

The interface of this class is very similar to std::set<fock>.

Member Function Documentation

applyFunction()

template<typename ExecPolicy >

State Basis::applyFunction

(

const FockAmpFunction &

f

)

const

Constructs a state from the basis using function f.

Parameters

[in]

f

– function to apply.

Returns

Constructed state.

Applies a function f to all Fock states of *this to compute a corresponding amplitude of a resulting state.

generateBasis()

Basis & Basis::generateBasis	(	const int	nphot,
		const int	modes,
		const Fock &	head = Fock()
	)

Generates a basis of all possible Fock states with modes modes and containing nphot photons.

Parameters

[in]	nphot	– number of photons in each Fock state.
[in]	modes	– number of modes in each Fock state.

Deprecated:

Parameters

[in]

head

– intended for internal usage. Normally empty Fock state should be passed.

Note

This funtion only appends elements to *this and never removes them. Therefore, if you want to freshly generate a basis, you should call basis::clear first.

operator*()

Basis Basis::operator*

(

const Basis &

b

)

const

Calculates a tensor product of two bases.

Returns a basis consisting of all possible elementwise tensor products of elements of *this and b.

postselect()

Basis Basis::postselect

(

const Fock &

ancilla

)

const

Returns a postselected basis after observing ancilla.

Parameters

[in]

ancilla

– ancilla's Fock state for postselection.

Returns

A basis after postselection.

Postselection of a basis \( B \) with the ancilla state \( | \mathrm{anc} \rangle = | a_0, a_2, \dots, a_A \rangle \) picks only Fock states from \( B \) with the heading (first \( A \) occupation numbers) which equals to \( | \mathrm{anc} \rangle \). The headings do not get to the new constructed basis. Note that currently there is no possibility to specify a position of ancilla modes.

For example, postselection of a basis

\[ \{ | 0000001 \rangle, | 1234567 \rangle, | 1239999 \rangle \} \]

with the ancilla \( | 123 \rangle \) results in the basis

\[ \{ | 4567 \rangle, | 9999 \rangle \}. \]

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The documentation for this class was generated from the following files:

• states.h
• states.cpp