# Quantum device¶

When the quantum algorithm is executed on the simulator, the expected value of the observed quantity can be calculated precisely because the probability amplitude of the quantum state is accessible. However, when the algorithm is actually executed on the actual device, the expected value is measured by sampling because it is impossible to know the amplitude of the probability of the quantum state with arbitrary accuracy. In order to obtain numerical results under similar conditions to those obtained in the real world, it is possible to select a simulated algorithm that includes the effects of measurement fluctuations.

## Type¶

The following `type`

s of `QuantumDevice`

are available:

*EXACT_SIMULATOR*: Calculate expectation values exactly from the probability amplitudes of the quantum states.*SAMPLING_SIMULATOR*: Calculate expectation from sampling.

If there is no input, *EXACT_SIMULATOR* is set as default value.

## Options¶

`sampling_random_seed`

: Set the seed value of random numbers for sampling (the default value is*1*).`flexible_shot_limit`

: Allow Qamuy to adjust the shot count automatically to be within limits specified by backend (the default value is*False*)

## Input example¶

```
"quantum_device": {
"type": "SAMPLING_SIMULATOR",
"sampling_random_seed": 1
}
```