# The Inner product operation of quantum state without measurement

**URL:** <https://discuss.pennylane.ai/t/the-inner-product-operation-of-quantum-state-without-measurement/2228>\
**Category:** PennyLane Help\
**Created:** [October 19, 2022, 3:41pm UTC](https://discuss.pennylane.ai/t/the-inner-product-operation-of-quantum-state-without-measurement/2228 "2022-10-19T15:41:10Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![CatalinaAlbornoz](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/catalinaalbornoz/32/1196_2.png) [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\
**Post date:** [October 20, 2022, 10:33pm UTC](https://discuss.pennylane.ai/t/the-inner-product-operation-of-quantum-state-without-measurement/2228/2 "2022-10-20T22:33:35Z")

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Hi @zj-lucky, the inner product between two states can be computed using the SWAP test.

You can learn more about implementing it in PennyLane [here](http://discuss.pennylane.ai/t/swap-test-using-different-registers/801/2)!

Please let me know if this solves your question.

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