Analog computing

Once a Hamiltonian is encoded and the Schedule is converted to a Job, one can perform a simulation by sending this Job to a dedicated analog QPU.

Qaptiva-HPC is equipped with such simulators - DMPSTraj and QutipQPU -.

Analog QPUs and simulation modes

	Qubit simulations				Bosonic simulations	Fermionic simulations
	Noiseless	Noisy
		With jump operators		With stochastic noise
		deterministic	stochastic
DMPSTRaj	Yes	No	Yes	No	No	No
QutipQPU	Yes	Yes	Yes	Yes	Yes	Yes

• DMPSTraj compresses the quantum state in a Matrix Product State (MPS, a type of Tensor Network), and can thus potentially reach a higher number of qubits than QutipQPU or AnalogQPU. The lower the entanglement entropy of the state, the higher the number of qubits can be simulated. The time evolution is performed by Trotterization of the hamiltonian. Noise in the form of jump operators is treated stochastically, with one of several trajectory algorithms, the choice of which can impact performances.

• QutipQPU is based on the QuTiP library. It can simulate the evolution of Bosonic Hamiltonians (i.e. more than 2-level systems) in the presence (or not) of qubits, Fermionic Hamiltonians, as well as Hamiltonians with stochastic noise with an arbitrary user-specified Power Spectral Density (PSD).

The analog QPUs above are able to measure more than one Observable per simulation. One can achieve this by passing a list of the other desired observables to be measured to the observables argument of the to_job() method of the Schedule. Together with the final expectation values \(\left<O\right>(t_{f})\) provided in the Result fields value, one can also access \(\left<O\right>(t)\), i.e. the measured values at all times via value_data.

Noiseless simulations

02_analog/01_noiseless_an.rst

Noisy simulations

02_analog/02_noisy_an.rst

Bosonic simulations

02_analog/03_bosonic.rst

Fermionic simulations

02_analog/04_fermionic.rst

We provide some of the key applications of analog quantum computations: