State Preparation

Functions:

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prepare_uniform_trimmed_state

prepare_uniform_trimmed_state(
m: CInt,
q: QArray[QBit]
) -> None

[Qmod Classiq-library function] Initializes a quantum variable in a uniform superposition of the first m computational basis states: $$\left|\text{q}\right\rangle = \frac{1}{\sqrt{m}}\sum_{i=0}^{m-1}{|i\rangle}$$ The number of allocated qubits would be $\left\lceil\log_2\{m\}\right\rceil$. The function is especially useful when m is not a power of 2. Parameters:

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prepare_uniform_interval_state

prepare_uniform_interval_state(
start: CInt,
end: CInt,
q: QNum
) -> None

[Qmod Classiq-library function] Initializes a quantum variable in a uniform superposition of the specified interval in the computational basis states: $$\left|\text{q}\right\rangle = \frac{1}{\sqrt{\text{end} - \text{start}}}\sum_{i=\text{start}}^{\text{end}-1}{|i\rangle}$$ The number of allocated qubits would be $\left\lceil\log_2\{\left(\text\{end\}\right)\}\right\rceil$. Parameters:

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prepare_ghz_state

prepare_ghz_state(
size: CInt,
q: Output[QArray[QBit]]
) -> None

[Qmod Classiq-library function] Initializes a quantum variable in a Greenberger-Horne-Zeilinger (GHZ) state. i.e., a balanced superposition of all ones and all zeros, on an arbitrary number of qubits.. Parameters:

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prepare_exponential_state

prepare_exponential_state(
rate: CInt,
q: QArray[QBit]
) -> None

[Qmod Classiq-library function] Prepares a quantum state with exponentially decreasing amplitudes. The state is prepared in the computational basis, with the amplitudes of the states decreasing exponentially with the index of the state: $$P(n) = \frac{1}{Z} e^{- \text{rate} \cdot n}$$ Parameters:

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prepare_bell_state

prepare_bell_state(
state_num: CInt,
qpair: Output[QArray[QBit, Literal[2]]]
) -> None

[Qmod Classiq-library function] Initializes a quantum array of size 2 in one of the four Bell states. Parameters:

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inplace_prepare_int

inplace_prepare_int(
value: CInt,
target: QNum
) -> None

[Qmod Classiq-library function] This function is deprecated. Use in-place-xor assignment statement in the form target-var ^= quantum-expression or inplace_xor(quantum-expression, target-var**)** instead. Transitions a quantum variable in the zero state $|0\rangle$ into the computational basis state $|\text\{value\}\rangle$. In the general case, the function performs a bitwise-XOR, i.e. transitions the state $|\psi\rangle$ into $|\psi \oplus \text\{value\}\rangle$. Parameters:

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prepare_int

prepare_int(
value: CInt,
out: Output[QNum[Literal[‘floor(log(value, 2)) + 1’]]]
) -> None

[Qmod Classiq-library function] This function is deprecated. Use assignment statement in the form target-var |= quantum-expression or assign(quantum-expression, target-var**)** instead. Initializes a quantum variable to the computational basis state $|\text\{value\}\rangle$. The number of allocated qubits is automatically computed from the value, and is the minimal number required for representation in the computational basis. Parameters:

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prepare_complex_amplitudes

prepare_complex_amplitudes(
magnitudes: CArray[CReal],
phases: list[float],
out: Output[QArray[QBit, Literal[‘log(magnitudes.len, 2)’]]]
) -> None

[Qmod Classiq-library function] Initializes and prepares a quantum state with amplitudes and phases for each state according to the given parameters, in polar representation. Parameters:

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inplace_prepare_complex_amplitudes

inplace_prepare_complex_amplitudes(
magnitudes: CArray[CReal],
phases: list[float],
target: QArray[QBit, Literal[‘log(magnitudes.len, 2)’]]
) -> None

[Qmod Classiq-library function] Prepares a quantum state with amplitudes and phases for each state according to the given parameters, in polar representation. Expects to act on an initialized zero state $|0\rangle$. Parameters:

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prepare_dicke_state

prepare_dicke_state(
k: int,
qvar: QArray[QBit]
) -> None

[Qmod Classiq-library function] Prepares a Dicke state with k excitations over the provided quantum register. A Dicke state of n qubits with k excitations is an equal superposition of all basis states with exactly k qubits in the $|1\rangle$ state and $(n - k)$ qubits in the $|0\rangle$ state. For example, $\mathrm\{Dicke\}(2, 1) = (|01\rangle + |10\rangle) / \sqrt(2)$. In the general case it is defined to be: $\mathrm\{Dicke\}(n, k) = \frac\{1\}\{\sqrt\{\binom\{n\}\{k\}\}\} \sum_\{x \in \\{0,1\\}^n,\, |x| = k\} |x\rangle$ Parameters:

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prepare_dicke_state_unary_input

prepare_dicke_state_unary_input(
max_k: int,
qvar: QArray[QBit]
) -> None

[Qmod Classiq-library function] Prepares a Dicke state with a variable number of excitations based on a unary-encoded input. The Dicke state is defined to be: $\mathrm\{Dicke\}(n, k) = \frac\{1\}\{\sqrt\{\binom\{n\}\{k\}\}\} \sum_\{x \in \\{0,1\\}^n,\, |x| = k\} |x\rangle$ The input register qvar is expected to already be initialized in a unary encoding: the value k is represented by a string of k ones followed by zeros, e.g., k = 3 -> |11100…0>. The function generates a Dicke state with k excitations over a new quantum register, where 0 <= k < max_k. Parameters:

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prepare_basis_state

prepare_basis_state(
state: list[bool],
arr: Output[QArray]
) -> None

[Qmod Classiq-library function] Initializes a quantum array in the specified basis state. Parameters:

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prepare_linear_amplitudes

prepare_linear_amplitudes(
x: QArray
) -> None

[Qmod Classiq-library function] Initializes a quantum variable in a state with linear amplitudes: angle = rac\{1\}\{Z\}\sum_\{x=0\}^\{2^n-1\}\{x|x angle\}$$ Where $Z$ is a normalization constant. Based on the paper https://quantum-journal.org/papers/q-2024-03-21-1297/pdf/ **Parameters:** | Name | Type | Description | Default | | ---- | ---- | ----------- | ------- | | `x` | `QArray` | The quantum register to prepare. | *required* | ### prepare_sparse_amplitudes <pre><code>prepare_sparse_amplitudes( states: list[int], amplitudes: list[complex], out: Output[QArray] ) -> None</code></pre> [Qmod Classiq-library function] Initializes and prepares a quantum state with the given (complex) amplitudes. The input is given sparse format, as a list of non-zero states and their corresponding amplitudes. Notice that the function is only suitable sparse states. Inspired by https://arxiv.org/abs/2310.19309. For example, `prepare_sparse_amplitudes([1, 8], [np.sqrt(0.5), np.sqrt(0.5)], out)` will and allocate it to be of size 4 qubits, and prepare it in the state sqrt(0.5)`|1>` + sqrt(0.5)`|8>`. Complexity: Asymptotic gate complexity is $O(dn)$ where d is the number of states and n is the required number of qubits. **Parameters:** | Name | Type | Description | Default | | ---- | ---- | ----------- | ------- | | `states` | `list[int]` | A list of distinct computational basis indices to populate. Each integer corresponds to the basis state in the computational basis. | *required* | | `amplitudes` | `list[complex]` | A list of complex amplitudes for the corresponding entries in `states`. Must have the same length as `states`. | *required* | | `out` | `Output[QArray]` | The allocated quantum variable. | *required* | ### inplace_prepare_sparse_amplitudes <pre><code>inplace_prepare_sparse_amplitudes( states: list[int], amplitudes: list[complex], target: QArray ) -> None</code></pre> [Qmod Classiq-library function] Prepares a quantum state with the given (complex) amplitudes. The input is given sparse format, as a list of non-zero states and their corresponding amplitudes. Notice that the function is only suitable sparse states. Inspired by https://arxiv.org/abs/2310.19309. For example, `inplace_prepare_sparse_amplitudes([1, 8], [np.sqrt(0.5), np.sqrt(0.5)], target)` will prepare the state sqrt(0.5)`|1>` + sqrt(0.5)`|8>` on the target variable, assuming it starts in the `|0>` state. Complexity: Asymptotic gate complexity is $O(dn)$ where d is the number of states and n is the target number of qubits. **Parameters:** | Name | Type | Description | Default | | ---- | ---- | ----------- | ------- | | `states` | `list[int]` | A list of distinct computational basis indices to populate. Each integer corresponds to the basis state in the computational basis. | *required* | | `amplitudes` | `list[complex]` | A list of complex amplitudes for the corresponding entries in `states`. Must have the same length as `states`. | *required* | | `target` | `QArray` | The quantum variable on which the state is to be prepared. Its size must be sufficient to represent all states in `states`. | *required* |