Register

class pulser.register.Register(qubits, **kwargs)

Bases: BaseRegister, RegDrawer

A 2D quantum register containing a set of qubits.

Parameters:

qubits (Mapping[Any, ArrayLike | pm.TensorLike]) – Dictionary with the qubit names as keys and their position coordinates (in μm) as values (e.g. {‘q0’:(2, -1, 0), ‘q1’:(-5, 10, 0), …}).

Attributes

dimensionality	The dimensionality of the coordinates (2 or 3).
layout	The layout used to define the register.
qubit_ids	The qubit IDs of this register.
qubits	Dictionary of the qubit names and their position coordinates.
sorted_coords	The sorted coordinates.

Methods

coords_hex_hash	Returns the idempotent hash of the coordinates.
define_detuning_map	Defines a DetuningMap for some qubits of the register.
draw	Draws the entire register.
find_indices	Computes indices of qubits.
from_abstract_repr	Deserialize a register from an abstract JSON object.
from_coordinates	Creates the register from an array of coordinates.
hexagon	Creates the register with the qubits in a hexagonal layout.
max_connectivity	Initializes the register with maximum connectivity for a device.
rectangle	Creates a rectangular array of qubits on a square lattice.
rectangular_lattice	Creates a rectangular array of qubits on a rectangular lattice.
rotated	Makes a new rotated register.
square	Creates the register with the qubits in a square array.
to_abstract_repr	Serializes the register into an abstract JSON object.
triangular_lattice	Creates the register with the qubits in a triangular lattice.
with_automatic_layout	Replicates the register with an automatically generated layout.

Signatures

coords_hex_hash()

Returns the idempotent hash of the coordinates.

Returns:

An hexstring encoding the hash.

Return type:

str

Note

This hash will be returned as an hexstring without the ‘0x’ prefix (unlike what is returned by ‘hex()’).

define_detuning_map(detuning_weights, slug=None)

Defines a DetuningMap for some qubits of the register.

Parameters:

• detuning_weights (Mapping[str, float]) – A mapping between the IDs of the targeted qubits and detuning weights (between 0 and 1).

• slug (str | None, default: None) – An optional identifier for the detuning map.

Return type:

DetuningMap

Returns:

A DetuningMap associating detuning weights to the trap coordinates of the targeted qubits.

draw(with_labels=True, blockade_radius=None, draw_graph=True, draw_half_radius=False, qubit_colors={}, fig_name=None, kwargs_savefig={}, custom_ax=None, show=True)

Draws the entire register.

Parameters:

• with_labels (bool, default: True) – If True, writes the qubit ID’s next to each qubit.

• blockade_radius (float | None, default: None) – The distance (in μm) between atoms below the Rydberg blockade effect occurs.

• draw_half_radius (bool, default: False) – Whether or not to draw the half the blockade radius surrounding each atoms. If True, requires blockade_radius to be defined.

• draw_graph (bool, default: True) – Whether or not to draw the interaction between atoms as edges in a graph. Will only draw if the blockade_radius is defined.

• qubit_colors (Mapping[str, str], default: {}) – By default, atoms are drawn with a common default color. If this parameter is present, it replaces the colors for the specified atoms. Non-specified ones are stilled colored with the default value.

• fig_name (str | None, default: None) – The name on which to save the figure. If None the figure will not be saved.

• kwargs_savefig (dict, default: {}) – Keywords arguments for matplotlib.pyplot.savefig. Not applicable if fig_name is None.

• custom_ax (Axes | None, default: None) – If present, instead of creating its own Axes object, the function will use the provided one. Warning: if fig_name is set, it may save content beyond what is drawn in this function.

• show (bool, default: True) – Whether or not to call plt.show() before returning. When combining this plot with other ones in a single figure, one may need to set this flag to False.

Return type:

None

Note

When drawing half the blockade radius, we say there is a blockade effect between atoms whenever their respective circles overlap. This representation is preferred over drawing the full Rydberg radius because it helps in seeing the interactions between atoms.

find_indices(id_list)

Computes indices of qubits.

This can especially be useful when building a Pulser Sequence with a parameter denoting qubits.

Example

Let reg be a register with qubit Ids “a”, “b” and “c”:

>>> reg.find_indices(["a", "b", "c", "a"])

It returns [0, 1, 2, 0], following the qubit order of the register.

Then, it is possible to use these indices when building a sequence, typically by assigning them to an array of variables that can be provided as an argument to target_index and phase_shift_index.

Parameters:

id_list (Sequence[str]) – IDs of the qubits to find.

Return type:

list[int]

Returns:

Indices of the qubits to denote, only valid for the given mapping.

static from_abstract_repr(obj_str)

Deserialize a register from an abstract JSON object.

Parameters:

obj_str (str) – the JSON string representing the register encoded in the abstract JSON format.

Return type:

Register

classmethod from_coordinates(coords, center=True, prefix=None, labels=None, **kwargs)

Creates the register from an array of coordinates.

Parameters:

• coords (ArrayLike | pm.TensorLike) – The coordinates of each qubit to include in the register.

• center (bool, default: True) – Whether or not to center the entire array around the origin.

• prefix (Optional[str], default: None) – The prefix for the qubit ids. If defined, each qubit id starts with the prefix, followed by an int from 0 to N-1 (e.g. prefix=’q’ -> IDs: ‘q0’, ‘q1’, ‘q2’, …).

• labels (Optional[abcSequence[QubitId]], default: None) – The list of qubit ids. If defined, each qubit id will be set to the corresponding value.

Return type:

T

Returns:

A register with qubits placed on the given coordinates.

classmethod hexagon(layers, spacing=4.0, prefix=None)

Creates the register with the qubits in a hexagonal layout.

Parameters:

• layers (int) – Number of layers around a central atom.

• spacing (float | TensorLike, default: 4.0) – The distance between neighbouring qubits in μm.

• prefix (str | None, default: None) – The prefix for the qubit ids. If defined, each qubit id starts with the prefix, followed by an int from 0 to N-1 (e.g. prefix=’q’ -> IDs: ‘q0’, ‘q1’, ‘q2’, …).

Return type:

Register

Returns:

A register with qubits placed in a hexagonal layout.

classmethod max_connectivity(n_qubits, device, spacing=None, prefix=None)

Initializes the register with maximum connectivity for a device.

In order to maximize connectivity, the basic pattern is the triangle. Atoms are first arranged as layers of hexagons around a central atom. Extra atoms are placed in such a manner that C3 and C6 rotational symmetries are enforced as often as possible.

Parameters:

• n_qubits (int) – Number of qubits.

• device (BaseDevice) – The device whose constraints must be obeyed.

• spacing (float | TensorLike | None, default: None) – The distance between neighbouring qubits in μm. If omitted, the minimal distance for the device is used.

• prefix (str | None, default: None) – The prefix for the qubit ids. If defined, each qubit id starts with the prefix, followed by an int from 0 to N-1 (e.g. prefix=’q’ -> IDs: ‘q0’, ‘q1’, ‘q2’, …).

Return type:

Register

Returns:

A register with qubits placed for maximum connectivity.

classmethod rectangle(rows, columns, spacing=4.0, prefix=None)

Creates a rectangular array of qubits on a square lattice.

Parameters:

• rows (int) – Number of rows.

• columns (int) – Number of columns.

• spacing (float | TensorLike, default: 4.0) – The distance between neighbouring qubits in μm.

• prefix (str | None, default: None) – The prefix for the qubit ids. If defined, each qubit id starts with the prefix, followed by an int from 0 to N-1 (e.g. prefix=’q’ -> IDs: ‘q0’, ‘q1’, ‘q2’, …)

Return type:

Register

Returns:

A register with qubits placed in a rectangular array.

classmethod rectangular_lattice(rows, columns, row_spacing=4.0, col_spacing=2.0, prefix=None)

Creates a rectangular array of qubits on a rectangular lattice.

Parameters:

• rows (int) – Number of rows.

• columns (int) – Number of columns.

• row_spacing (float | TensorLike, default: 4.0) – The distance between rows in μm.

• col_spacing (float | TensorLike, default: 2.0) – The distance between columns in μm.

• prefix (str | None, default: None) – The prefix for the qubit ids. If defined, each qubit id starts with the prefix, followed by an int from 0 to N-1 (e.g. prefix=’q’ -> IDs: ‘q0’, ‘q1’, ‘q2’, …)

Return type:

Register

Returns:

Register with qubits placed in a rectangular array on a rectangular lattice.

rotated(degrees)

Makes a new rotated register.

All coordinates are rotated counter-clockwise around the origin.

Parameters:

degrees (float) – The angle of rotation in degrees.

Returns:

A new register rotated around the origin by the given angle.

Return type:

Register

classmethod square(side, spacing=4.0, prefix=None)

Creates the register with the qubits in a square array.

Parameters:

• side (int) – Side of the square in number of qubits.

• spacing (float | TensorLike, default: 4.0) – The distance between neighbouring qubits in μm.

• prefix (str | None, default: None) – The prefix for the qubit ids. If defined, each qubit id starts with the prefix, followed by an int from 0 to N-1 (e.g. prefix=’q’ -> IDs: ‘q0’, ‘q1’, ‘q2’, …).

Return type:

Register

Returns:

A register with qubits placed in a square array.

to_abstract_repr()

Serializes the register into an abstract JSON object.

Return type:

str

classmethod triangular_lattice(rows, atoms_per_row, spacing=4.0, prefix=None)

Creates the register with the qubits in a triangular lattice.

Initializes the qubits in a triangular lattice pattern, more specifically a triangular lattice with horizontal rows, meaning the triangles are pointing up and down.

Parameters:

• rows (int) – Number of rows.

• atoms_per_row (int) – Number of atoms per row.

• spacing (float | TensorLike, default: 4.0) – The distance between neighbouring qubits in μm.

• prefix (str | None, default: None) – The prefix for the qubit ids. If defined, each qubit id starts with the prefix, followed by an int from 0 to N-1 (e.g. prefix=’q’ -> IDs: ‘q0’, ‘q1’, ‘q2’, …).

Return type:

Register

Returns:

A register with qubits placed in a triangular lattice.

with_automatic_layout(device, layout_slug=None)

Replicates the register with an automatically generated layout.

The generated RegisterLayout can be accessed via Register.layout.

Parameters:

• device (Device) – The device constraints for the layout generation.

• layout_slug (str | None, default: None) – An optional slug for the generated layout.

Raises:

• RuntimeError – If the automatic layout generation fails to meet the device constraints.

• NotImplementedError – When the register has differentiable coordinates (ie torch Tensors with requires_grad=True).

Returns:

A new register instance with identical qubit IDs and coordinates but also the newly generated RegisterLayout.

Return type:

Register

property dimensionality: int

The dimensionality of the coordinates (2 or 3).

property layout: RegisterLayout | None

The layout used to define the register.

property qubit_ids: tuple[str, ...]

The qubit IDs of this register.

property qubits: dict[str, AbstractArray]

Dictionary of the qubit names and their position coordinates.

property sorted_coords: ndarray

The sorted coordinates.