# Default.qubit question

**URL:** <https://discuss.pennylane.ai/t/default-qubit-question/368>\
**Category:** PennyLane Help\
**Created:** [March 26, 2020, 3:00pm UTC](https://discuss.pennylane.ai/t/default-qubit-question/368 "2020-03-26T15:00:32Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![James\_Ellis](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/james_ellis/32/159_2.png) [@James\_Ellis](https://discuss.pennylane.ai/u/James_Ellis)\
**Post date:** [March 26, 2020, 3:00pm UTC](https://discuss.pennylane.ai/t/default-qubit-question/368/1 "2020-03-26T15:00:32Z")

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Hi,

Is default.qubit based off any certain quantum computer?

What are the main differences between a 5 qubit simulator (default.qubit) and say a 5 qubit IBM quantum computer in terms of the results they produce?

Thanks for your help 😃

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**Author:** ![nathan](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/nathan/32/85_2.png) [@nathan](https://discuss.pennylane.ai/u/nathan)\
**Post date:** [March 26, 2020, 4:44pm UTC](https://discuss.pennylane.ai/t/default-qubit-question/368/2 "2020-03-26T16:44:14Z")

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Hi @James_Ellis,

`default.qubit` is a general simulator, not based on any particular physical device (more specifically, it is a pure-state qubit-model simulator). It simulates what a perfect, noise-free quantum computer would do.

The main difference with, say, an IBM machine is that the IBM machine will have some noise/imperfections which deviate from the theoretical ideal. As time goes by, and physical quantum computers improve, you can expect the real-world devices to track closer and closer to what the ideal simulators produce.