squadds.calcs package

Submodules

squadds.calcs.qubit module

class squadds.calcs.qubit.QubitHamiltonian(analysis)

Bases: ABC

abstract E01(EJ, EC)

Calculate the energy difference between the ground state (|0>) and the first excited state (|1>) of a qubit.

Parameters:

• EJ (-) – Josephson energy of the qubit.

• EC (-) – Charging energy of the qubit.

Returns:

Energy difference between the ground state and the first excited state.

Return type:

• float

abstract E01_and_anharmonicity(EJ, EC)

Calculate the energy of the first excited state (E01) and the anharmonicity of a qubit.

Parameters:

• EJ (-) – Josephson energy of the qubit.

• EC (-) – Charging energy of the qubit.

Returns:

Energy of the first excited state. - anharmonicity (float): Anharmonicity of the qubit.

Return type:

• E01 (float)

abstract EC(cross_to_claw, cross_to_ground)

Performs error correction on the qubit.

Parameters:

• cross_to_claw (float) – The cross-talk probability from the qubit to the claw.

• cross_to_ground (float) – The cross-talk probability from the qubit to the ground.

Returns:

None

abstract EJ(f_q, alpha)

Calculate the Josephson energy (EJ) of a qubit.

Parameters:

• f_q (float) – The qubit frequency in Hz.

• alpha (float) – The anharmonicity parameter.

Returns:

The Josephson energy (EJ) in Joules.

Return type:

float

abstract EJ_and_LJ(f_q, alpha)

Calculate the Josephson energy (EJ) and the Josephson inductance (LJ) for a given qubit frequency (f_q) and anharmonicity (alpha).

Parameters:

• f_q (float) – The qubit frequency in Hz.

• alpha (float) – The anharmonicity of the qubit in Hz.

Returns:

A tuple containing the Josephson energy (EJ) and the Josephson inductance (LJ).

Return type:

tuple

abstract add_cavity_coupled_H_params()

Add parameters for cavity-coupled Hamiltonian.

abstract add_qubit_H_params()

Add parameters for the Hamiltonian of the qubit.

abstract calculate_target_quantities(f_res, alpha, g, w_q, N, Z_0=50)

Calculate the target quantities for a qubit.

Parameters:

• f_res (-) – The resonance frequency of the qubit.

• alpha (-) – The anharmonicity of the qubit.

• g (-) – The coupling strength between the qubit and the resonator.

• w_q (-) – The frequency of the qubit.

• N (-) – The number of photons in the resonator.

• Z_0 (-) – The characteristic impedance of the resonator. Default is 50 Ohms.

Returns:

None

abstract chi()

Calculate the chi parameter for the qubit.

abstract g_alpha_freq(C, C_c, EJ, f_r, res_type, Z0=50)

Calculate the alpha and frequency of a qubit.

Parameters:

• C (-) – Capacitance of the qubit.

• C_c (-) – Coupling capacitance.

• EJ (-) – Josephson energy.

• f_r (-) – Resonator frequency.

• res_type (-) – Resonator type.

• Z0 (-) – Characteristic impedance. Default is 50.

Returns:

Qubit anharmonicity. - freq (float): Qubit frequency.

Return type:

• alpha (float)

abstract g_and_alpha(C, C_c, f_q, EJ, f_r, res_type, Z0=50)

Calculate the coupling strength (g) and anharmonicity (alpha) of a qubit.

Parameters:

• C (-) – Capacitance of the qubit.

• C_c (-) – Coupling capacitance.

• f_q (-) – Frequency of the qubit.

• EJ (-) – Josephson energy of the qubit.

• f_r (-) – Resonator frequency.

• res_type (-) – Type of resonator.

• Z0 (-) – Characteristic impedance of the transmission line. Default is 50 Ohms.

Returns:

Coupling strength of the qubit. - alpha (float): Anharmonicity of the qubit.

Return type:

• g (float)

abstract g_from_cap_matrix(C, C_c, EJ, f_r, res_type, Z0=50)

Calculate the coupling strength ‘g’ of a qubit from the capacitance matrix.

Parameters:

• C (-) – The capacitance matrix.

• C_c (-) – The coupling capacitance.

• EJ (-) – The Josephson energy.

• f_r (-) – The resonant frequency.

• res_type (-) – The type of resonator.

• Z0 (-) – The characteristic impedance. Default is 50 Ohms.

Returns: - g (float): The coupling strength of the qubit.

abstract get_freq_alpha_fixed_LJ(fig4_df, LJ_target)

Calculate the frequency alpha for a fixed LJ value.

Parameters:

• fig4_df (DataFrame) – The DataFrame containing the data for Fig. 4.

• LJ_target (float) – The target LJ value.

Returns:

The calculated frequency alpha.

Return type:

float

abstract plot_data(data_frame)

Plot the given data frame.

Parameters:

data_frame (pandas.DataFrame) – The data frame to be plotted.

squadds.calcs.transmon_cross module

#!TODO: Generalize the half-wave cavity method usage

squadds.calcs.transmon_cross.EC_numba(cross_to_claw, cross_to_ground)

squadds.calcs.transmon_cross.Ec_from_Cs(Cs)

Calculate the charging energy (Ec) in GHz from the capacitance (Cs) in fF.

class squadds.calcs.transmon_cross.TransmonCrossHamiltonian(analysis)

Bases: QubitHamiltonian

Class representing the Hamiltonian for a transmon qubit in a cross-coupled configuration.

Initialize the TransmonCrossHamiltonian object.

- analysis

The analysis object associated with the Hamiltonian.

E01(EJ, EC, ng=0, ncut=30)

Calculate the energy of the first excited state (E01) of a transmon qubit.

Parameters:

• EJ (-) – Josephson energy of the transmon qubit.

• EC (-) – Charging energy of the transmon qubit.

• ng (-) – Offset charge on the transmon qubit. Default is 0.

• ncut (-) – Truncation level for the transmon qubit’s Hilbert space. Default is 30.

Returns:

Energy of the first excited state (E01) of the transmon qubit.

Return type:

• E01 (float)

E01_and_anharmonicity(EJ, EC, ng=0, ncut=30)

Calculate the energy of the first excited state (E01) and the anharmonicity (alpha) of a transmon qubit.

Parameters:

• EJ (-) – Josephson energy of the transmon qubit.

• EC (-) – Charging energy of the transmon qubit.

• ng (-) – Offset charge on the transmon qubit. Defaults to 0.

• ncut (-) – Truncation level for the transmon qubit’s Hilbert space. Defaults to 30.

Returns:

Energy of the first excited state (E01) in GHz. - alpha (float): Anharmonicity (alpha) in MHz.

Return type:

• E01 (float)

EC(cross_to_claw, cross_to_ground)

Calculate the charging energy (EC) of the transmon qubit.

Parameters:

• cross_to_claw (-) – Capacitance between the cross and the claw.

• cross_to_ground (-) – Capacitance between the cross and the ground.

Returns:

The charging energy of the transmon qubit.

Return type:

• EC

EJ(w_q, alpha)

Calculate the Josephson energy (EJ) based on the given qubit frequency (w_q) and anharmonicity (alpha).

Parameters:

• w_q (-) – The qubit frequency.

• alpha (-) – The anharmonicity of the qubit.

Returns:

The Josephson energy of the qubit.

Return type:

• EJ

EJ_and_LJ(w_q, alpha, *args, **kwargs)

Calculate the Josephson energy (EJ) and Josephson inductance (Lj) based on the given qubit frequency (w_q) and anharmonicity (alpha).

Parameters:

• w_q (-) – The qubit frequency.

• alpha (-) – The anharmonicity of the qubit.

Returns:

The Josephson energy of the qubit. - Lj: The Josephson inductance of the qubit.

Return type:

• EJ

add_cavity_coupled_H_params(num_chunks='auto', Z_0=50)

Add cavity-coupled Hamiltonian parameters to the dataframe.

This method calculates the coupling strength ‘g_MHz’ between the transmon qubit and the cavity, based on the capacitance matrix, transmon parameters, cavity frequency, resonator type, and characteristic impedance.

Parameters:

• num_chunks (-) – The number of chunks to split the DataFrame into for parallel processing. Default is “auto” which sets the number of chunks to the number of logical CPUs.

• Z_0 (-) – The characteristic impedance of the transmission line. Default is 50 ohms.

Returns:

None

add_cavity_coupled_H_params_chunk(chunk, Z_0=50)

Add cavity-coupled Hamiltonian parameters to the DataFrame chunk.

This method calculates the coupling strength ‘g_MHz’ between the transmon qubit and the cavity,

Parameters:

• chunk (-) – The DataFrame chunk to which the parameters will be added.

• Z_0 (-) – The characteristic impedance of the transmission line. Default is 50 ohms.

Returns:

The DataFrame chunk with the added parameters.

Return type:

• chunk

add_qubit_H_params()

Add qubit Hamiltonian parameters to the DataFrame.

This method calculates and adds the qubit Hamiltonian parameters, such as EC, EJ, and EJEC, to the DataFrame.

Parameters:

None

Returns:

None

add_qubit_H_params_chunk(df)

Add qubit Hamiltonian parameters to the DataFrame chunk.

This method calculates and adds the qubit Hamiltonian parameters, such as EC, EJ, and EJEC,

Parameters:

df (-) – The DataFrame chunk to which the parameters will be added.

Returns:

The DataFrame chunk with the added parameters

Return type:

• df

calculate_target_quantities(f_res, alpha, g, w_q, res_type, Z_0=50)

Calculate the target quantities (C_q, C_c, EJ, EC, EJ_EC_ratio) based on the given parameters.

Parameters:

• f_res (-) – The resonator frequency.

• alpha (-) – The anharmonicity of the qubit.

• g (-) – The coupling strength between the qubit and the resonator.

• w_q (-) – The qubit frequency.

• res_type (-) – The type of resonator.

• Z_0 (-) – The characteristic impedance of the resonator.

Returns:

The total capacitance of the qubit. - C_c: The coupling capacitance between the qubit and the resonator. - EJ: The Josephson energy of the qubit. - EC: The charging energy of the qubit. - EJ_EC_ratio: The ratio of EJ to EC.

Return type:

• C_q

chi(EJ, EC, g, f_r)

Calculate the full cavity frequency shift between |0> and |1> states of a qubit using g, f_r, f_q, and alpha. It uses the result derived using 2nd-order perturbation theory (equation 9 in SQuaDDS paper). :param - EJ: Josephson energy of the transmon qubit. :type - EJ: float :param - EC: Charging energy of the transmon qubit. :type - EC: float :param - g: The coupling strength between the qubit and the cavity. :type - g: float :param - f_r: The resonant frequency of the cavity. :type - f_r: float :param - f_q: The frequency spacing between the first two qubit levels. :type - f_q: float

Returns:

The full dispersive shift of the cavity

Return type:

• chi (float)

g_alpha_freq(C, C_c, EJ, f_r, res_type, Z0=50)

Calculate the coupling strength, anharmonicity, and transition frequency of a transmon qubit.

Parameters:

• C (-) – Total capacitance of the transmon qubit.

• C_c (-) – Coupling capacitance between the transmon qubit and the resonator.

• EJ (-) – Josephson energy of the transmon qubit.

• f_r (-) – Resonator frequency.

• res_type (-) – Type of resonator. Must be either ‘half’ or ‘quarter’.

• Z0 (-) – Characteristic impedance of the transmission line. Defaults to 50.

Returns:

A tuple containing the coupling strength (g), anharmonicity (alpha), and transition frequency (freq).

Return type:

• (g, alpha, freq) (tuple)

g_and_alpha(C, C_c, f_q, EJ, f_r, res_type, Z0=50)

Calculate the coupling strength (g) and anharmonicity (alpha) based on the given parameters.

Parameters:

• C (-) – The capacitance between the qubit and the ground.

• C_c (-) – The coupling capacitance between the qubit and the resonator.

• f_q (-) – The qubit frequency.

• EJ (-) – The Josephson energy of the qubit.

• f_r (-) – The resonator frequency.

• res_type (-) – The type of resonator.

• Z0 (-) – The characteristic impedance of the resonator.

Returns:

The coupling strength between the qubit and the resonator. - alpha: The anharmonicity of the qubit.

Return type:

• g

g_from_cap_matrix(C, C_c, EJ, f_r, res_type, Z0=50)

Calculate the coupling strength ‘g’ between a transmon qubit and a resonator based on the capacitance matrix.

Parameters:

• C (-) – Capacitance between the qubit and the resonator (in femtofarads, fF).

• C_c (-) – Coupling capacitance of the resonator (in femtofarads, fF).

• EJ (-) – Josephson energy of the qubit (in GHz).

• f_r (-) – Resonator frequency (in GHz).

• res_type (-) – Type of resonator. Can be ‘half’ or ‘quarter’.

• Z0 (-) – Characteristic impedance of the transmission line (in ohms). Default is 50 ohms.

Returns:

Coupling strength ‘g’ between the qubit and the resonator (in MHz).

Return type:

• g (float)

get_freq_alpha_fixed_LJ(fig4_df, LJ_target)

Calculate the frequencies and anharmonicities of transmons with a fixed LJ value.

Parameters:

• fig4_df (-) – DataFrame containing the values of EC for different transmons.

• LJ_target (-) – Target value of LJ in nH.

Returns:

List of frequencies of the transmons. - alpha: List of anharmonicities of the transmons.

Return type:

• freq

parallel_process_dataframe(df, num_chunks, Z_0=50)

Process the DataFrame in parallel.

This method splits the DataFrame into chunks and processes each chunk in parallel.

Parameters:

• df (-) – The DataFrame to be processed.

• num_chunks (-) – The number of chunks to split the DataFrame into.

• Z_0 (-) – The characteristic impedance of the transmission line. Default is 50

Returns:

The DataFrame with the added parameters.

Return type:

• df

plot_data(data_frame)

Plot the data from the given DataFrame.

Parameters:

data_frame (-) – The DataFrame containing the data to be plotted.

squadds.calcs.transmon_cross.g_from_cap_matrix_numba(C, C_c, EJ, f_r, res_type, Z0=50)

!TODO: resolve the error : “The keyword argument ‘parallel=True’ was specified but no transformation for parallel execution was possible.” for this method

squadds.calcs.transmon_cross.φ0 = 3.2910597847545335e-16

Numba decorated methods

Module contents