Ket-based concrete QState backend using qpp. More...

#include <q2ns-qstate-ket.h>

Inheritance diagram for q2ns::QStateKet:

Collaboration diagram for q2ns::QStateKet:

Public Member Functions
	QStateKet (std::size_t numQubits)
	Construct the \|0...0> state on numQubits qubits.

	QStateKet (qpp::ket state)
	Construct from an existing ket.

int64_t	AssignStreams (int64_t stream) override
	Assign RNG streams for deterministic randomness.

std::size_t	NumQubits () const override
	Return the number of logical qubits in the state.

void	Print (std::ostream &os) const override
	Print a human-readable representation of the state.

void	Apply (const QGate &g, const std::vector< q2ns::Index > &targets) override
	Apply a gate to the given target qubits.

std::shared_ptr< QState >	MergeDisjoint (const QState &other) const override
	Return the disjoint merge of this state and another ket backend.

MeasureResult	Measure (q2ns::Index target, q2ns::Basis basis=q2ns::Basis::Z) override
	Measure one qubit in the requested basis and split the result.

const qpp::ket &	GetKet () const
	Return the underlying ket.

void	SetKet (const qpp::ket &k)
	Replace the underlying ket.

qpp::cmat	GetDensityMatrix () const
	Return the density matrix \|psi><psi\| of the current ket.

Public Member Functions inherited from q2ns::QState
virtual	~QState ()
	Virtual destructor.

StateId	GetStateId () const
	Get the registry-assigned state id.

void	SetStateId (StateId id)
	Set the registry-assigned state id.

virtual void	Apply (const QGate &g, const std::vector< Index > &targets)=0
	Apply a gate to the given target indices.

Static Private Member Functions
static void	ValidateKet (const qpp::ket &k)
	Validate basic ket properties.

Private Attributes
qpp::ket	state_
	Pure state ket.

Additional Inherited Members
Protected Member Functions inherited from q2ns::QState
void	PrintHeader (std::ostream &os, const char *backendName) const
	Print a standard backend header.

Static Protected Member Functions inherited from q2ns::QState
static uint64_t	SplitMix64 (uint64_t x)
	Mix a 64-bit value deterministically.

static uint64_t	DeriveSeed64 (uint32_t seed, uint32_t run, int64_t stream, uint64_t salt)
	Derive a deterministic 64-bit seed from ns-3 seed/run and a stream.

static std::seed_seq	MakeSeedSeq (uint64_t s64)
	Build a std::seed_seq from a 64-bit seed.

static void	CheckSeedRunNonZero (uint32_t seed, uint32_t run)
	Abort if ns-3 seed or run is zero.

template<uint64_t SALT>
static bool	ShouldReseed (uint32_t seed, uint32_t run, int64_t stream)
	Return whether a backend-global RNG should be reseeded.

template<uint64_t SALT, typename ReseedFn >
static int64_t	AssignStreamsGlobal (int64_t stream, ReseedFn reseed_fn)
	Helper for backends that reseed a global RNG source.

Detailed Description

Ket-based concrete QState backend using qpp.

QStateKet stores an N-qubit pure state as a qpp::ket and implements the common QState interface.

This is the default backend and supports:

general unitary gate application
disjoint merge by tensor product
single-qubit measurement with split return semantics

It also exposes backend-specific helpers for direct ket access and conversion to a density matrix.

Constructors validate basic ket structure such as power-of-two dimension and norm close to one.

See also: QState; QStateDM

Definition at line 46 of file q2ns-qstate-ket.h.

Constructor & Destructor Documentation

◆ QStateKet() [1/2]

q2ns::QStateKet::QStateKet ( std::size_t numQubits )

explicit

Construct the |0...0> state on numQubits qubits.

Parameters

numQubits Number of qubits.

Definition at line 51 of file q2ns-qstate-ket.cc.

References q2ns::QState::AssignStreamsGlobal(), and state_.

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◆ QStateKet() [2/2]

q2ns::QStateKet::QStateKet ( qpp::ket state )

explicit

Construct from an existing ket.

Parameters

state Pure state ket.

Exceptions

std::invalid_argument if the ket is empty, not a column vector, not of dimension 2^N, or not normalized.

Definition at line 58 of file q2ns-qstate-ket.cc.

References state_, and ValidateKet().

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Member Function Documentation

◆ Apply()

void q2ns::QStateKet::Apply	(	const QGate &	g,
		const std::vector< q2ns::Index > &	targets
	)

override

Apply a gate to the given target qubits.

Parameters

g	Gate descriptor.
targets	Target qubit indices.

Definition at line 88 of file q2ns-qstate-ket.cc.

References q2ns::QState::AssignStreamsGlobal(), q2ns::Custom, q2ns::MatrixOf(), and state_.

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◆ AssignStreams()

int64_t q2ns::QStateKet::AssignStreams ( int64_t stream )

overridevirtual

Assign RNG streams for deterministic randomness.

This seeds qpp's random source for measurement and other stochastic qpp operations used by this backend.

Parameters

stream Starting stream index.

Returns: Number of streams consumed.

Reimplemented from q2ns::QState.

Definition at line 64 of file q2ns-qstate-ket.cc.

References q2ns::QState::AssignStreamsGlobal(), and q2ns::QState::MakeSeedSeq().

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◆ GetDensityMatrix()

qpp::cmat q2ns::QStateKet::GetDensityMatrix ( ) const

Return the density matrix |psi><psi| of the current ket.

Returns: Density matrix corresponding to the current pure state.

See also: GetKet

Definition at line 179 of file q2ns-qstate-ket.cc.

References state_.

◆ GetKet()

const qpp::ket & q2ns::QStateKet::GetKet ( ) const

Return the underlying ket.

Returns: Reference to the backend ket.

See also: SetKet; GetDensityMatrix

Definition at line 166 of file q2ns-qstate-ket.cc.

References state_.

◆ Measure()

QState::MeasureResult q2ns::QStateKet::Measure	(	q2ns::Index	target,
		q2ns::Basis	basis = `q2ns::Basis::Z`
	)

overridevirtual

Measure one qubit in the requested basis and split the result.

The returned measured state is a 1-qubit collapsed state expressed in the requested measurement basis. The survivors state contains the remaining qubits in their original relative order.

Parameters

target	Index of the qubit to measure.
basis	Measurement basis. Defaults to Z.

Returns: Measurement result containing outcome, measured state, and survivor state.

Implements q2ns::QState.

Definition at line 124 of file q2ns-qstate-ket.cc.

References q2ns::QState::AssignStreamsGlobal(), q2ns::H, NumQubits(), q2ns::S, state_, q2ns::X, q2ns::Y, and q2ns::Z.

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◆ MergeDisjoint()

std::shared_ptr< QState > q2ns::QStateKet::MergeDisjoint ( const QState & other ) const

overridevirtual

Return the disjoint merge of this state and another ket backend.

The merged qubit order is [this-qubits..., other-qubits...].

Parameters

other Other state to merge with.

Returns: Newly allocated merged state.

Implements q2ns::QState.

Definition at line 112 of file q2ns-qstate-ket.cc.

References q2ns::QState::AssignStreamsGlobal(), and state_.

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◆ NumQubits()

std::size_t q2ns::QStateKet::NumQubits ( ) const

overridevirtual

Return the number of logical qubits in the state.

Returns: Number of logical qubits.

Implements q2ns::QState.

Definition at line 75 of file q2ns-qstate-ket.cc.

References state_.

Referenced by Measure().

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◆ Print()

void q2ns::QStateKet::Print ( std::ostream & os ) const

overridevirtual

Print a human-readable representation of the state.

Parameters

os	Output stream.

Implements q2ns::QState.

Definition at line 81 of file q2ns-qstate-ket.cc.

References q2ns::QState::AssignStreamsGlobal(), q2ns::QState::PrintHeader(), and state_.

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◆ SetKet()

void q2ns::QStateKet::SetKet ( const qpp::ket & k )

Replace the underlying ket.

Parameters

k	New backend ket.

Exceptions

std::invalid_argument if the ket is empty, not a column vector, not of dimension 2^N, or not normalized.

See also: GetKet

Definition at line 172 of file q2ns-qstate-ket.cc.

References q2ns::QState::AssignStreamsGlobal(), state_, and ValidateKet().

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◆ ValidateKet()

void q2ns::QStateKet::ValidateKet ( const qpp::ket & k )

staticprivate

Validate basic ket properties.

Parameters

k	Ket to validate.

Definition at line 26 of file q2ns-qstate-ket.cc.

References q2ns::QState::AssignStreamsGlobal().

Referenced by QStateKet(), and SetKet().

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Member Data Documentation

◆ state_

qpp::ket q2ns::QStateKet::state_

private

Pure state ket.

Definition at line 149 of file q2ns-qstate-ket.h.

Referenced by Apply(), GetDensityMatrix(), GetKet(), Measure(), MergeDisjoint(), NumQubits(), Print(), QStateKet(), QStateKet(), and SetKet().

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

Public Member Functions

Static Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QStateKet() [1/2]

◆ QStateKet() [2/2]

Member Function Documentation

◆ Apply()

◆ AssignStreams()

◆ GetDensityMatrix()

◆ GetKet()

◆ Measure()

◆ MergeDisjoint()

◆ NumQubits()

◆ Print()

◆ SetKet()

◆ ValidateKet()

Member Data Documentation

◆ state_