NoiseModel

class pulser.noise_model.NoiseModel(runs=None, samples_per_run=1, state_prep_error=0.0, p_false_pos=0.0, p_false_neg=0.0, temperature=0.0, laser_waist=None, amp_sigma=0.0, detuning_sigma=0.0, detuning_hf_psd=(), detuning_hf_omegas=(), relaxation_rate=0.0, dephasing_rate=0.0, trap_waist=0.0, trap_depth=None, hyperfine_dephasing_rate=0.0, depolarizing_rate=0.0, eff_noise_rates=(), eff_noise_opers=(), with_leakage=False, disable_doppler=False)

Bases: object

Specifies the noise model parameters for emulation.

Supported noise types:

• leakage: Adds an error state ‘x’ to the computational basis, that can interact with the other states via an effective noise channel. Must be defined with an effective noise channel, but is incompatible with dephasing and depolarizing noise channels.

• relaxation: Noise due to a decay from the Rydberg to the ground state (parametrized by relaxation_rate), commonly characterized experimentally by the T1 time.

• dephasing: Random phase (Z) flip (parametrized by dephasing_rate), commonly characterized experimentally by the T2* time.

• depolarizing: Quantum noise where the state is turned into the maximally mixed state with rate depolarizing_rate. While it does not describe a physical phenomenon, it is a commonly used tool to test the system under a uniform combination of phase flip (Z) and bit flip (X) errors.

• eff_noise: General effective noise channel defined by the set of collapse operators eff_noise_opers and their corresponding rates eff_noise_rates.

• doppler: Local atom detuning due to termal motion of the atoms and Doppler effect with respect to laser frequency. Parametrized by the temperature field. Can be disabled with the disable_doppler field.

• register: Thermal fluctuations in the register positions, parametrized by temperature, trap_waist and, trap_depth, which must all be defined.

  (1) Plane standard deviation fluctuation given by: \(\sigma^{xy} = \sqrt{\frac{T w²}{4 U_{trap}}}\), where T is temperature, w is the trap waist and \(U_{trap}\) is the trap depth.

  (2) Off plane standard deviation fluctuation given by: \(\sigma^z = \frac{\pi}{\lambda}\sqrt{2} w \sigma^{xy}\), where \(\lambda\) is the trap wavelength with a constant value of 0.85 µm.

• amplitude: Gaussian damping due to finite laser waist and laser amplitude fluctuations. Parametrized by laser_waist and amp_sigma.

• detuning: Detuning fluctuations consisting of two components:

  (1) constant offset (zero-frequency), parameterized by detuning_sigma

  (2) time-dependent high-frequency fluctuations, defined by the power spectral density (PSD) detuning_hf_psd over the relevant detuning_hf_omegas angular frequency support. \(\delta_{hf}(t) = \sum_k \sqrt{2*\Delta \omega_k*\mathrm{PSD}_k} * \cos(\omega_k * t + \phi_k)\) where \(\phi_k \backsim U[0, 2\pi)\) (uniform random phase), and \(\Delta \omega_k = \omega_{k+1} - \omega_k\).

• SPAM: SPAM errors. Parametrized by state_prep_error, p_false_pos and p_false_neg.

Parameters:

• runs (int | None, default: None) – When reconstructing the Hamiltonian from random noise is necessary, this determines how many times that happens. Not to be confused with the number of times the resulting bitstring distribution is sampled when calculating bitstring counts.

• samples_per_run (int, default: 1) – Number of samples per noisy Hamiltonian. Useful for cutting down on computing time, but unrealistic. Deprecated since v1.6, use only `runs`.

• state_prep_error (float, default: 0.0) – The state preparation error probability. Defaults to 0.

• p_false_pos (float, default: 0.0) – Probability of measuring a false positive. Defaults to 0.

• p_false_neg (float, default: 0.0) – Probability of measuring a false negative. Defaults to 0.

• temperature (float, default: 0.0) – Temperature, set in µK, of the atoms in the array. Also sets the standard deviation of the speed of the atoms. Defaults to 0.

• laser_waist (float | None, default: None) – Waist of the gaussian lasers, set in µm, for global pulses. Assumed to be the same for all global channels.

• amp_sigma (float, default: 0.0) – Dictates the fluctuation in amplitude of a channel from run to run as a standard deviation of a normal distribution centered in 1. Assumed to be the same for all channels (though each channel has its own randomly sampled value in each run).

• detuning_sigma (float, default: 0.0) – Dictates the fluctuation in detuning (in rad/µs) of a channel from run to run as a standard deviation of a normal distribution centered in 0. Assumed to be the same for all channels (though each channel has its own randomly sampled value in each run). This noise is additive. Defaults to 0.

• trap_waist (float, default: 0.0) – The waist of each optical trap at the focal point (in µm). Defaults to 0.

• trap_depth (float | None, default: None) – The potential energy well depth that confines the atoms (in µK). Defaults to None.

• detuning_hf_psd (tuple[float, ...], default: ()) – Power Spectral Density (PSD) is 1D tuple (in rad/µs) provided together with detuning_hf_omegas define high frequency noise contribution of time dependent detuning (in rad/µs). Must either be empty or a tuple with at least two values, matching the length of detuning_hf_omegas. Default is ().

• detuning_hf_omegas (tuple[float, ...], default: ()) – 1D tuple (in rad/µs) of relevant angular frequency support for the PSD. Along with the PSD, it is required to define high frequency noise contribution of time dependent detuning (in rad/µs). Must either be empty or a tuple with at least two values, matching the length of detuning_hf_psd. Default is ().

• relaxation_rate (float, default: 0.0) – The rate of relaxation from the Rydberg to the ground state (in 1/µs). Corresponds to 1/T1. Defaults to 0.

• dephasing_rate (float, default: 0.0) – The rate of a dephasing occuring (in 1/µs) in a Rydberg state superpostion. Only used if a Rydberg state is involved. Corresponds to 1/T2*. Defaults to 0.

• hyperfine_dephasing_rate (float, default: 0.0) – The rate of dephasing occuring (in 1/µs) between hyperfine ground states. Only used if the hyperfine state is involved. Defaults to 0.

• depolarizing_rate (float, default: 0.0) – The rate (in 1/µs) at which a depolarizing error occurs. Defaults to 0.

• eff_noise_rates (tuple[float, ...], default: ()) – The rate associated to each effective noise operator (in 1/µs). Defaults to 0.

• eff_noise_opers (tuple[ArrayLike, ...], default: ()) – The operators for the effective noise model. Defaults to 0.

• with_leakage (bool, default: False) – Whether or not to include an error state in the computations (default to False).

• disable_doppler (bool, default: False) – Whether or not to disable the doppler noise, even if the temperature is defined. In this way, ‘register’ noise (which requires ‘temperature’) can be activated on its own (i.e without doppler).

Attributes

amp_sigma
dephasing_rate
depolarizing_rate
detuning_hf_omegas
detuning_hf_psd
detuning_sigma
disable_doppler
eff_noise_opers
eff_noise_rates
hyperfine_dephasing_rate
laser_waist
p_false_neg
p_false_pos
relaxation_rate
runs
samples_per_run
state_prep_error
temperature
trap_depth
trap_waist
with_leakage
noise_types

Methods

from_abstract_repr	Deserialize a noise model from an abstract JSON object.
to_abstract_repr	Serializes the noise model into an abstract JSON object.

Signatures

static from_abstract_repr(obj_str)

Deserialize a noise model from an abstract JSON object.

Parameters:

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

Return type:

NoiseModel

to_abstract_repr()

Serializes the noise model into an abstract JSON object.

Return type:

str