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4-hand fixing
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a-corni committed Jan 10, 2025
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13 changes: 10 additions & 3 deletions docs/source/programming.md
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Expand Up @@ -34,6 +34,8 @@ If $d=2$ and $N=1$, you have the state of a qubit as above $\left|\Psi\right> =

</details>

<br>

### 2. Hamiltonian evolves the state

In quantum physics, the state of a quantum system evolves along time following the Schrödinger equation:
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<summary>Rotations on the Bloch sphere</summary>

In the Bloch sphere representation, this Hamiltonian describes a rotation around the axis $\overrightarrow{\Omega}(t) = (\Omega(t)\cos(\phi), -\Omega(t)\sin(\phi), -\delta(t))^T$, with angular velocity $\Omega_{eff}(t) = |\overrightarrow{\Omega}(t)| = \sqrt{\Omega^2(t) + \delta^2(t)}$. For a resonant pulse ($\delta(t)=0$) of duration $\Delta t$, we rotate of an angle $\int_0^{\Delta t} \Omega (t) dt$ around the fixed axis $(\cos(\phi), -\sin(\phi), 0)$ (on the equator of the Bloch sphere).

In the Bloch sphere representation, this Hamiltonian describes a rotation around the axis $\overrightarrow{\Omega}(t) = (\Omega(t)\cos(\phi), -\Omega(t)\sin(\phi), -\delta(t))^T$, with angular velocity $\Omega_{eff}(t) = |\overrightarrow{\Omega}(t)| = \sqrt{\Omega^2(t) + \delta^2(t)}$.

For a resonant pulse ($\delta(t)=0$) of duration $\Delta t$, we rotate of an angle $\int_0^{\Delta t} \Omega (t) dt$ around the fixed axis $(\cos(\phi), -\sin(\phi), 0)$ (on the equator of the Bloch sphere).

:::{figure} files/bloch_rotation_a_b.png
:align: center
Expand All @@ -83,6 +88,8 @@ $|b\rangle$, with Rabi frequency $\Omega(t)$, detuning $\delta(t)$ and phase $\p

</details>

<br>

:::{important}
With Pulser, you program the driving Hamiltonian by setting $\Omega(t)$, $\delta(t)$ and $\phi(t)$, all the while Pulser ensures that you respect the constraints of your chosen device.
:::
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The interaction operator $\hat{U}_{ij}$ is composed of an entangling operator and an interaction strength.

:::{note}
The interaction Hamiltonian is constant along time. It is always on, no matter the values of the drive Hamiltonian (even if the values of the parameters $\Omega$, $\delta$, $\phi$ are equal to $0$ over a time $\Delta t$).
The interaction Hamiltonian is constant over time. It is always on, no matter the values of the drive Hamiltonian (even if the values of the parameters $\Omega$, $\delta$, $\phi$ are equal to $0$ over a time $\Delta t$).
:::

##### Ising Hamiltonian
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The `Register` defines the position of the atoms. This determines:

- the number of atoms to use in the quantum computation, i.e, the size of the system (let's note it $N$).
- the distance between the atoms, the $R_{ij} (1\le i, j\le N)$ parameters in the [interaction Hamiltonian](programming.md#22-interaction-hamiltonian).
- the distance between the atoms, the $R_{ij}\ (1\le i, j\le N)$ parameters in the [interaction Hamiltonian](programming.md#22-interaction-hamiltonian).

### 3. Pick the Channels

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