# pmm_tools.models.parity_qubit_tunnel

*module*

Two real Kitaev chains joined by normal hopping, with no middle dot.

Fock ordering: (L1,...,LN,R1,...,RN); fixed total parity. The bridge is
t_c (c_LN^dagger c_R1 + h.c.), without pairing. All parameters are in micro-eV.
Both superconducting phases are zero, matching the current noise campaign.
The many-body Hamiltonian is assembled by second_quantization through the
existing open-chain constructor. No bridge elimination or low-energy
projection is made here, including when t_c exceeds the clean chain gap.

## pmm_tools.models.parity_qubit_tunnel.clean_parameters

*function*

```python
def clean_parameters(n_sites, coupling, gap)
```

Sweet spot t=Delta=gap/2, zero onsite energies, fixed normal link.

[View source](https://gitlab.kwant-project.org/qt/pmm_tools/-/blob/e412d66507a554f455ef935b755fc39f28ab4e05/pmm_tools/models/parity_qubit_tunnel.py#L48-L59)

## pmm_tools.models.parity_qubit_tunnel.clean_product_state

*function*

```python
def clean_product_state(n_sites, parameters, label='ee')
```

Clean isolated-chain ground states, restricted to their total parity.

[View source](https://gitlab.kwant-project.org/qt/pmm_tools/-/blob/e412d66507a554f455ef935b755fc39f28ab4e05/pmm_tools/models/parity_qubit_tunnel.py#L62-L80)

## pmm_tools.models.parity_qubit_tunnel.device_matrix_dict

*function* · *cached*

```python
def device_matrix_dict(n_sites, parity='even')
```

Map the 2N-site open-chain operators to two chains and a normal link.

[View source](https://gitlab.kwant-project.org/qt/pmm_tools/-/blob/e412d66507a554f455ef935b755fc39f28ab4e05/pmm_tools/models/parity_qubit_tunnel.py#L19-L45)