mindquantum.core.operators.FermionOperator
- class mindquantum.core.operators.FermionOperator(terms: Union[str, 'FermionOperator'] = None, coefficient: PRConvertible = 1.0, internal: bool = False)[source]
Definition of a Fermion Operator.
The Fermion Operator such as FermionOperator('9 4^ 3 3^') are used to represent \(a_9 a_4^\dagger a_3 a_3^\dagger\).
These are the Basic Operators to describe a fermionic system, such as a Molecular system. The FermionOperator are follows the anti-commutation relationship.
- Parameters
terms (Union[str, ParameterResolver]) – The input term of fermion operator. Default:
None.coefficient (Union[numbers.Number, str, Dict[str, numbers.Number], ParameterResolver]) – The coefficient for the corresponding single operators Default:
1.0.internal (bool) – Whether the first argument is internal c++ object of FermionOperator or not. Default:
False.
Examples
>>> from mindquantum.core.operators import FermionOperator >>> a_p_dagger = FermionOperator('1^') >>> a_p_dagger 1 [1^] >>> a_q = FermionOperator('0') >>> a_q 1 [0] >>> zero = FermionOperator() >>> zero 0 >>> identity= FermionOperator('') >>> identity 1 [] >>> para_op = FermionOperator('0 1^', 'x') >>> para_op -x [1^ 0] >>> para_dt = {'x':2} >>> op = para_op.subs(para_dt) >>> op -2 [1^ 0]
- astype(dtype)[source]
Convert to different data type.
Note
Converting a complex type FermionOperator to real type will ignore the image part of coefficient.
- Parameters
dtype (mindquantum.dtype) – new data type of fermion operator.
- Returns
FermionOperator, new fermion operator with given data type.
Examples
>>> from mindquantum.core.operators import FermionOperator >>> import mindquantum as mq >>> f = FermionOperator('0^', 2 + 3j) >>> f.dtype mindquantum.complex128 >>> f.astype(mq.float64) 2 [0^]
- compress(abs_tol=EQ_TOLERANCE)[source]
Eliminate the very small fermion string that close to zero.
- Parameters
abs_tol (float) – Absolute tolerance, must be at least 0.0. Default: EQ_TOLERANCE.
- Returns
FermionOperator, the compressed operator.
Examples
>>> from mindquantum.core.operators import FermionOperator >>> ham_compress = FermionOperator('0^ 1', 0.5) + FermionOperator('2^ 3', 1e-7) >>> ham_compress 1/2 [0^ 1] + 1/10000000 [2^ 3] >>> ham_compress.compress(1e-6) 1/2 [0^ 1] >>> ham_para_compress = FermionOperator('0^ 1', 0.5) + FermionOperator('2^ 3', 'X') >>> ham_para_compress 1/2 [0^ 1] + X [2^ 3] >>> ham_para_compress.compress(1e-7) 1/2 [0^ 1] + X [2^ 3]
- property constant: mindquantum.core.parameterresolver.parameterresolver.ParameterResolver
Return the coefficient of the identity fermion string.
- Returns
ParameterResolver, the coefficient of the identity fermion string.
- count_qubits()[source]
Calculate the number of qubits on which operator acts before removing the unused qubit.
- Returns
int, the qubits number before remove unused qubit.
Examples
>>> from mindquantum.core.operators import FermionOperator >>> a = FermionOperator("0^ 3") >>> a.count_qubits() 4
- property dtype
Get the data type of FermionOperator.
- dumps(indent: int = 4)[source]
Dump a FermionOperator into JSON(JavaScript Object Notation).
- Parameters
indent (int) – Then JSON array elements and object members will be pretty-printed with that indent level. Default:
4.- Returns
JSON (str), the JSON strings of this FermionOperator
Examples
>>> from mindquantum.core.operators import FermionOperator >>> f = FermionOperator('0', 1 + 2j) + FermionOperator('0^', 'a') >>> len(f.dumps()) 581
- static from_openfermion(of_ops)[source]
Convert openfermion fermion operator to mindquantum format.
- Parameters
of_ops (openfermion.FermionOperator) – fermion operator from openfermion.
- Returns
FermionOperator, fermion operator from mindquantum.
- get_coeff(term)[source]
Get coefficient of given term.
Examples
>>> from mindquantum.core.operators import FermionOperator >>> f = FermionOperator('0^ 1', 1.2) >>> f.get_coeff([(1, ''), (0, '^')]) ParameterResolver(dtype: float64, const: -1.200000) >>> f.get_coeff([(1, 0), (0, 1)]) ParameterResolver(dtype: float64, const: -1.200000)
- hermitian()[source]
Get the hermitian of a FermionOperator.
- Returns
FermionOperator, The hermitian of this FermionOperator.
Examples
>>> from mindquantum.core.operators import FermionOperator >>> a = FermionOperator("0^ 1", {"a": 1 + 2j}) >>> a.hermitian() (1 - 2j)*a [1^ 0]
- property imag: mindquantum.core.operators.fermion_operator.FermionOperator
Convert the coefficient to its imag part.
- Returns
Fermion, the imag part of this FermionOperator.
Examples
>>> from mindquantum.core.operators import FermionOperator >>> f = FermionOperator('0', 1 + 2j) + FermionOperator('0^', 'a') >>> f.imag 2 [0]
- property is_complex: bool
Return whether the FermionOperator instance is currently using complex coefficients.
- property is_singlet: bool
To verify whether this operator has only one term.
- Returns
bool, whether this operator has only one term.
- static loads(strs: str)[source]
Load JSON(JavaScript Object Notation) into a FermionOperator.
- Parameters
strs (str) – The dumped fermion operator string.
- Returns
FermionOperator, the FermionOperator loaded from JSON-formatted strings
Examples
>>> from mindquantum.core.operators import FermionOperator >>> f = FermionOperator('0', 1 + 2j) + FermionOperator('0^', 'a') >>> obj = FermionOperator.loads(f.dumps()) >>> obj == f True
- matrix(n_qubits: int = None, pr=None)[source]
Convert this fermion operator to csr_matrix under jordan_wigner mapping.
- Parameters
n_qubits (int) – The total qubit of final matrix. If None, the value will be the maximum local qubit number. Default: None.
pr (ParameterResolver, dict, numpy.ndarray, list, numbers.Number) – The parameter resolver for parameterized FermionOperator. Default: None.
- normal_ordered()[source]
Return the normal ordered form of the Fermion Operator.
- Returns
FermionOperator, the normal ordered FermionOperator.
Examples
>>> from mindquantum.core.operators import FermionOperator >>> origin = FermionOperator('0 1^') >>> origin 1.0 [0 1^] >>> origin.normal_ordered() -1.0 [1^ 0]
- property params_name
Get all parameters of this operator.
- property real: mindquantum.core.operators.fermion_operator.FermionOperator
Convert the coefficient to its real part.
- Returns
FermionOperator, the real part of this FermionOperator.
Examples
>>> from mindquantum.core.operators import FermionOperator >>> f = FermionOperator('0', 1 + 2j) + FermionOperator('0^', 'a') >>> f.real 1 [0] + a [0^]
- relabel(logic_qubits: List[int])[source]
Relabel the qubit according to the given logic qubits order.
- Parameters
logic_qubits (List[int]) – The label of logic qubits. For example, if logic_qubits is [2, 0, 1], original qubit 0 will label as 2.
Examples
>>> from mindquantum.core.operators import FermionOperator >>> o = FermionOperator('3^ 2 1 0') >>> o 1 [3^ 2 1 0] >>> o.relabel([1, 3, 0, 2]) -1 [3 2^ 1 0]
- singlet()[source]
Split the single string operator into every word.
- Returns
List[FermionOperator], The split word of the string.
- Raises
RuntimeError – if the size of terms is not equal to 1.
Examples
>>> from mindquantum.core.operators import FermionOperator >>> ops = FermionOperator("1^ 2", 1) >>> print(ops.singlet()) [1 [2], 1 [1^]]
- singlet_coeff()[source]
Get the coefficient of this operator, if the operator has only one term.
- Returns
ParameterResolver, the coefficient of this single string operator.
- Raises
RuntimeError – if the size of terms is not equal to 1.
Examples
>>> from mindquantum.core.operators import FermionOperator >>> ops = FermionOperator("1^ 2", "a") >>> print(ops) -a [2 1^] >>> print(ops.singlet_coeff()) -a
- split()[source]
Split the coefficient and the operator.
- Returns
List[List[ParameterResolver, FermionOperator]], the split result.
Examples
>>> from mindquantum.core.operators import FermionOperator >>> a = FermionOperator('0', 'a') + FermionOperator('1^', 1.2) >>> for i, j in a.split(): ... print(i, j) a, 1 [0] 1.2, 1 [1^]
- subs(params_value: PRConvertible)[source]
Replace the symbolical representation with the corresponding value.
- Parameters
params_value (Union[Dict[str, numbers.Number], ParameterResolver]) – the value of variable in coefficient.
Examples
>>> from mindquantum.core.operators import FermionOperator >>> from mindquantum.core.parameterresolver import ParameterResolver >>> f = FermionOperator('0^', ParameterResolver({'a': 2.0}, 3.0)) >>> f 2*a + 3 [0^] >>> f.subs({'a': 1.5}) 6 [0^]
- property terms: Dict[Tuple[int, int], mindquantum.core.parameterresolver.parameterresolver.ParameterResolver]
Get the terms of a FermionOperator.