Stabilizer concrete QState backend using stab::AffineState. More...

#include <q2ns-qstate-stab.h>

Inheritance diagram for q2ns::QStateStab:

Collaboration diagram for q2ns::QStateStab:

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

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

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

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

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

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

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

std::shared_ptr< QState >	Clone () const
	Return a clone of this stabilizer state.

const stab::AffineState &	GetAffineState () const
	Return the underlying AffineState.

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.

Private Member Functions
void	RotateIntoZBasis_ (Index q, Basis basis)
	Rotate a local basis so that measuring Z implements the requested basis.

void	RemoveQubit_ (Index target)
	Remove one qubit while preserving survivor order.

Static Private Member Functions
static std::shared_ptr< QStateStab >	Synth1QEigenstate_ (Basis basis, int bit)
	Build a 1-qubit basis eigenstate for a measurement outcome.

Private Attributes
std::size_t	numQubits_ {0}
	Number of logical qubits.

stab::AffineState	psi_
	Underlying stabilizer state.

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

Stabilizer concrete QState backend using stab::AffineState.

QStateStab supports Clifford-state simulation using a vendored stab::AffineState implementation.

Supported operations include:

1-qubit Clifford gates I, H, S, SDG, X, Y, Z
2-qubit Clifford gates CNOT, CZ, SWAP
single-qubit projective measurement in X, Y, and Z bases
disjoint merge by tensor product

This backend does not support arbitrary custom unitary gates.

See also: QState; QGateKind

Definition at line 48 of file q2ns-qstate-stab.h.

Constructor & Destructor Documentation

◆ QStateStab()

q2ns::QStateStab::QStateStab ( std::size_t numQubits )

explicit

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

Parameters

numQubits Number of qubits.

Definition at line 23 of file q2ns-qstate-stab.cc.

Member Function Documentation

◆ Apply()

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

overridevirtual

Apply a supported Clifford gate to the given target qubits.

Parameters

g	Gate descriptor.
t	Target qubit indices.

Implements q2ns::QState.

Definition at line 49 of file q2ns-qstate-stab.cc.

References q2ns::QState::AssignStreamsGlobal(), q2ns::CNOT, q2ns::Custom, q2ns::CZ, q2ns::H, q2ns::I, psi_, q2ns::S, q2ns::SDG, q2ns::SWAP, q2ns::X, q2ns::Y, and q2ns::Z.

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◆ AssignStreams()

int64_t q2ns::QStateStab::AssignStreams ( int64_t stream )

overridevirtual

Assign RNG streams for deterministic randomness.

This seeds the underlying stab random source used by measurement and other stochastic backend operations.

Parameters

stream Starting stream index.

Returns: Number of streams consumed.

Reimplemented from q2ns::QState.

Definition at line 28 of file q2ns-qstate-stab.cc.

References q2ns::QState::AssignStreamsGlobal().

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◆ Clone()

std::shared_ptr< QState > q2ns::QStateStab::Clone ( ) const

inline

Return a clone of this stabilizer state.

Returns: Newly allocated copy of this state.

Definition at line 113 of file q2ns-qstate-stab.h.

◆ GetAffineState()

const stab::AffineState & q2ns::QStateStab::GetAffineState ( ) const

inline

Return the underlying AffineState.

Returns: Reference to the backend stabilizer state.

Definition at line 121 of file q2ns-qstate-stab.h.

References psi_.

◆ Measure()

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

overridevirtual

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

The returned measured state is a 1-qubit stabilizer eigenstate in the requested 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 178 of file q2ns-qstate-stab.cc.

References q2ns::QState::AssignStreamsGlobal(), numQubits_, q2ns::QState::MeasureResult::outcome, psi_, RotateIntoZBasis_(), and Synth1QEigenstate_().

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◆ MergeDisjoint()

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

overridevirtual

Return the disjoint merge of this state and another stabilizer 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 205 of file q2ns-qstate-stab.cc.

References q2ns::QState::AssignStreamsGlobal(), numQubits_, and psi_.

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◆ NumQubits()

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

overridevirtual

Return the number of logical qubits in the state.

Returns: Number of logical qubits.

Implements q2ns::QState.

Definition at line 36 of file q2ns-qstate-stab.cc.

References numQubits_.

◆ Print()

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

overridevirtual

Print a human-readable representation of the state.

Parameters

os	Output stream.

Implements q2ns::QState.

Definition at line 42 of file q2ns-qstate-stab.cc.

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

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◆ RemoveQubit_()

void q2ns::QStateStab::RemoveQubit_ ( Index target )

private

Remove one qubit while preserving survivor order.

The target is swapped to the end and then dropped from the underlying AffineState.

Parameters

target Qubit to remove.

Definition at line 158 of file q2ns-qstate-stab.cc.

References q2ns::QState::AssignStreamsGlobal(), numQubits_, and psi_.

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◆ RotateIntoZBasis_()

void q2ns::QStateStab::RotateIntoZBasis_	(	Index	q,
		Basis	basis
	)

private

Rotate a local basis so that measuring Z implements the requested basis.

X measurement is implemented as H then Z. Y measurement is implemented as SDG then H then Z.

Parameters

q	Target qubit.
basis	Requested measurement basis.

Definition at line 107 of file q2ns-qstate-stab.cc.

References q2ns::QState::AssignStreamsGlobal(), psi_, q2ns::X, q2ns::Y, and q2ns::Z.

Referenced by Measure().

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◆ Synth1QEigenstate_()

std::shared_ptr< QStateStab > q2ns::QStateStab::Synth1QEigenstate_	(	Basis	basis,
		int	bit
	)

staticprivate

Build a 1-qubit basis eigenstate for a measurement outcome.

Parameters

basis	Measurement basis.
bit	Outcome bit.

Returns: Newly allocated 1-qubit stabilizer state.

Definition at line 126 of file q2ns-qstate-stab.cc.

References q2ns::QState::AssignStreamsGlobal(), q2ns::X, q2ns::Y, and q2ns::Z.

Referenced by Measure().

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Member Data Documentation

◆ numQubits_

std::size_t q2ns::QStateStab::numQubits_ {0}

private

Number of logical qubits.

Definition at line 155 of file q2ns-qstate-stab.h.

Referenced by Measure(), MergeDisjoint(), NumQubits(), and RemoveQubit_().

◆ psi_

stab::AffineState q2ns::QStateStab::psi_

private

Underlying stabilizer state.

Definition at line 156 of file q2ns-qstate-stab.h.

Referenced by Apply(), GetAffineState(), Measure(), MergeDisjoint(), Print(), RemoveQubit_(), and RotateIntoZBasis_().

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

Public Member Functions

Private Member Functions

Static Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QStateStab()

Member Function Documentation

◆ Apply()

◆ AssignStreams()

◆ Clone()

◆ GetAffineState()

◆ Measure()

◆ MergeDisjoint()

◆ NumQubits()

◆ Print()

◆ RemoveQubit_()

◆ RotateIntoZBasis_()

◆ Synth1QEigenstate_()

Member Data Documentation

◆ numQubits_

◆ psi_