Struct Layout 

pub struct Layout { /* private fields */ }

Maps circuit logical qubits to physical qubits on a quantum device.

A layout owns the set of physical qubits available to a placement or routing step. Every logical qubit present in the layout has exactly one physical mapping. A physical qubit may be vacant.

Auxiliary qubit ownership and lifetime are intentionally outside this type. From the layout perspective, an auxiliary logical qubit behaves like any other logical qubit after it is explicitly Layout::binded.

Implementations

impl Layout

pub fn new( logical: Vec<LogicalQubit>, physical: Vec<PhysicalQubit>, init_map: Option<BTreeMap<LogicalQubit, PhysicalQubit>>, ) -> Result<Self, LayoutError>

Creates a layout and maps each supplied logical qubit to a physical qubit.

Entries in init_map are applied first. Remaining logical qubits are mapped to remaining physical qubits in the order supplied by logical and physical. Extra physical qubits remain vacant.

Errors

Returns LayoutError if:

• there are more logical qubits than physical qubits;
• the logical or physical qubit list contains duplicate entries;
• init_map references an undeclared logical or physical qubit;
• init_map maps multiple logical qubits to one physical qubit.

Example

use cqlib_core::device::{Layout, LogicalQubit, PhysicalQubit};
use std::collections::BTreeMap;

let logical = vec![LogicalQubit::new(0), LogicalQubit::new(1)];
let physical = vec![PhysicalQubit::new(100), PhysicalQubit::new(101)];

let mut init = BTreeMap::new();
init.insert(LogicalQubit::new(0), PhysicalQubit::new(101));

let layout = Layout::new(logical, physical, Some(init)).unwrap();
assert_eq!(
    layout.get_physical(LogicalQubit::new(0)),
    Some(PhysicalQubit::new(101)),
);

pub fn from_pairs( logical_physical: &[(u32, u32)], physical_count: u32, ) -> Result<Self, LayoutError>

Creates a layout from (logical, physical) qubit ID pairs.

Logical qubits are exactly the logical IDs that appear in logical_physical. Physical qubits are 0..physical_count; any physical qubit not referenced by a pair remains vacant.

Errors

Returns LayoutError if a logical ID appears more than once, a physical ID appears more than once, or any physical ID is outside 0..physical_count.

Example

use cqlib_core::device::{Layout, LogicalQubit, PhysicalQubit};

let layout = Layout::from_pairs(&[(0, 2), (1, 0)], 4).unwrap();

assert_eq!(
    layout.get_physical(LogicalQubit::new(0)),
    Some(PhysicalQubit::new(2)),
);
assert_eq!(layout.num_vacant_physical(), 2);

pub fn num_logical(&self) -> usize

Returns the number of mapped logical qubits.

pub fn num_physical(&self) -> usize

Returns the number of physical qubits available to the layout.

pub fn num_vacant_physical(&self) -> usize

Returns the number of physical qubits that do not carry a logical qubit.

pub fn get_physical(&self, logical: LogicalQubit) -> Option<PhysicalQubit>

Returns the physical qubit carrying logical, if it is bound.

pub fn get_logical(&self, physical: PhysicalQubit) -> Option<LogicalQubit>

Returns the logical qubit carried by physical, if the position is occupied.

pub fn logical_qubits(&self) -> impl Iterator<Item = LogicalQubit> + '_

Returns an iterator over mapped logical qubits.

pub fn physical_qubits(&self) -> impl Iterator<Item = PhysicalQubit> + '_

Returns an iterator over physical qubits available to the layout.

pub fn vacant_physical_qubits(&self) -> impl Iterator<Item = PhysicalQubit> + '_

Returns an iterator over vacant physical qubits.

pub fn is_physical_vacant(&self, physical: PhysicalQubit) -> bool

Returns whether physical belongs to the layout and is vacant.

pub fn l2p_map(&self) -> &BTreeMap<LogicalQubit, PhysicalQubit>

Returns the logical-to-physical qubit mapping.

pub fn p2l_map(&self) -> &BTreeMap<PhysicalQubit, LogicalQubit>

Returns the physical-to-logical qubit mapping.

pub fn bind( &mut self, logical: LogicalQubit, physical: PhysicalQubit, ) -> Result<(), LayoutError>

Binds an unmapped logical qubit to a vacant physical qubit.

This operation may introduce a new logical qubit to the layout. The caller is responsible for ensuring that the logical qubit exists in the circuit and is registered with the compiler resource manager when required.

Errors

Returns LayoutError::InvalidPhysicalQubit if physical does not belong to the layout. Returns LayoutError::LogicalQubitAlreadyBound or LayoutError::PhysicalQubitAlreadyOccupied if either qubit already participates in a mapping.

pub fn unbind( &mut self, logical: LogicalQubit, ) -> Result<PhysicalQubit, LayoutError>

Removes the mapping for logical and returns the released physical qubit.

pub fn swap_physical( &mut self, phys_a: PhysicalQubit, phys_b: PhysicalQubit, ) -> Result<(), LayoutError>

Swaps the logical qubits carried by two physical qubits.

Either physical qubit may be vacant. Swapping an occupied qubit with a vacant qubit moves the logical qubit to the vacant position.

Errors

Returns LayoutError::InvalidPhysicalQubit if either physical qubit does not belong to the layout.

Trait Implementations

impl Clone for Layout

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Layout

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Layout

fn default() -> Self

Returns the “default value” for a type.

impl Eq for Layout

impl PartialEq for Layout

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Layout