Layout
class Layout(input_dict=None)
Bases: object
Two-ways dict to represent a Layout.
construct a Layout from a bijective dictionary, mapping virtual qubits to physical qubits
Methods
add
Layout.add(virtual_bit, physical_bit=None)
Adds a map element between bit and physical_bit. If physical_bit is not defined, bit will be mapped to a new physical bit.
Parameters
- virtual_bit (tuple) – A (qu)bit. For example, (QuantumRegister(3, ‘qr’), 2).
- physical_bit (int) – A physical bit. For example, 3.
add_register
Layout.add_register(reg)
Adds at the end physical_qubits that map each bit in reg.
Parameters
reg (Register) – A (qu)bit Register. For example, QuantumRegister(3, ‘qr’).
combine_into_edge_map
Layout.combine_into_edge_map(another_layout)
Combines self and another_layout into an “edge map”.
For example:
self another_layout resulting edge map
qr_1 -> 0 0 <- q_2 qr_1 -> q_2
qr_2 -> 2 2 <- q_1 qr_2 -> q_1
qr_3 -> 3 3 <- q_0 qr_3 -> q_0The edge map is used to compose dags via, for example, compose.
Parameters
another_layout (Layout) – The other layout to combine.
Returns
A “edge map”.
Return type
dict
Raises
LayoutError – another_layout can be bigger than self, but not smaller. Otherwise, raises.
copy
Layout.copy()
Returns a copy of a Layout instance.
from_dict
Layout.from_dict(input_dict)
Populates a Layout from a dictionary.
The dictionary must be a bijective mapping between virtual qubits (tuple) and physical qubits (int).
Parameters
input_dict (dict) –
e.g.:
{(QuantumRegister(3, 'qr'), 0): 0,
(QuantumRegister(3, 'qr'), 1): 1,
(QuantumRegister(3, 'qr'), 2): 2}
Can be written more concisely as follows:
* virtual to physical::
{qr[0]: 0,
qr[1]: 1,
qr[2]: 2}
* physical to virtual::
{0: qr[0],
1: qr[1],
2: qr[2]}from_intlist
static Layout.from_intlist(int_list, *qregs)
Converts a list of integers to a Layout mapping virtual qubits (index of the list) to physical qubits (the list values).
Parameters
- int_list (list) – A list of integers.
- *qregs (QuantumRegisters) – The quantum registers to apply the layout to.
Returns
The corresponding Layout object.
Return type
Raises
LayoutError – Invalid input layout.
from_qubit_list
static Layout.from_qubit_list(qubit_list, *qregs)
Populates a Layout from a list containing virtual qubits, Qubit or None.
Parameters
- qubit_list (list) – e.g.: [qr[0], None, qr[2], qr[3]]
- *qregs (QuantumRegisters) – The quantum registers to apply the layout to.
Returns
the corresponding Layout object
Return type
Raises
LayoutError – If the elements are not Qubit or None
generate_trivial_layout
static Layout.generate_trivial_layout(*regs)
Creates a trivial (“one-to-one”) Layout with the registers and qubits in regs.
Parameters
*regs (Registers, Qubits) – registers and qubits to include in the layout.
Returns
A layout with all the regs in the given order.
Return type
get_physical_bits
Layout.get_physical_bits()
Returns the dictionary where the keys are physical (qu)bits and the values are virtual (qu)bits.
get_registers
Layout.get_registers()
Returns the registers in the layout [QuantumRegister(2, ‘qr0’), QuantumRegister(3, ‘qr1’)] :returns: A set of Registers in the layout :rtype: Set
get_virtual_bits
Layout.get_virtual_bits()
Returns the dictionary where the keys are virtual (qu)bits and the values are physical (qu)bits.
order_based_on_type
static Layout.order_based_on_type(value1, value2)
decides which one is physical/virtual based on the type. Returns (virtual, physical)
reorder_bits
Layout.reorder_bits(bits)
Given an ordered list of bits, reorder them according to this layout.
The list of bits must exactly match the virtual bits in this layout.
Parameters
bits (list[Bit]) – the bits to reorder.
Returns
ordered bits.
Return type
List
swap
Layout.swap(left, right)
Swaps the map between left and right.
Parameters
- left (tuple or int) – Item to swap with right.
- right (tuple or int) – Item to swap with left.
Raises
LayoutError – If left and right have not the same type.