# How to understand Tensor observables and Combined measurements from the perspective of quantum mechanics?
**URL:** https://discuss.pennylane.ai/t/how-to-understand-tensor-observables-and-combined-measurements-from-the-perspective-of-quantum-mechanics/2023
**Category:** PennyLane Help
**Created:** [July 7, 2022, 12:57am UTC](https://discuss.pennylane.ai/t/how-to-understand-tensor-observables-and-combined-measurements-from-the-perspective-of-quantum-mechanics/2023 "2022-07-07T00:57:59Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@RX1](https://discuss.pennylane.ai/u/RX1)
#### Post date: [July 7, 2022, 12:57am UTC](https://discuss.pennylane.ai/t/how-to-understand-tensor-observables-and-combined-measurements-from-the-perspective-of-quantum-mechanics/2023/1 "2022-07-07T00:57:59Z")
This doubt comes from [https://pennylane.readthedocs.io/en/stable/introduction/measurements.html](https://pennylane.readthedocs.io/en/stable/introduction/measurements.html)
pennylane mentioned two measurements, I can’t tell the difference between the two. Such as H=0.5Z+1Yand H=0.5Z⊗1Y.
---
### Author:  [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)
#### Post date: [July 7, 2022, 7:05pm UTC](https://discuss.pennylane.ai/t/how-to-understand-tensor-observables-and-combined-measurements-from-the-perspective-of-quantum-mechanics/2023/2 "2022-07-07T19:05:31Z")
Hi @RX1,
I’m not sure what measurements you’re referring to since we don’t have any additions or scalar multiplications in the measurements there. Is your question about tensor products?
To learn more about tensor products you can go to our [I.11 node](https://codebook.xanadu.ai/I.11) in the Xanadu Quantum Codebook. You can also learn more about measurements in node[I.9](https://codebook.xanadu.ai/I.9).
I also encourage you to read this [blog](https://pennylane.ai/blog/2022/06/how-to-do-measurements-in-pennylane/) made by one of our residents, Joana Fraxanet, which talks about measurements.
I hope some of this helps! If not please feel free to expand on your question.
---
### Author:  [@RX1](https://discuss.pennylane.ai/u/RX1)
#### Post date: [July 13, 2022, 8:32am UTC](https://discuss.pennylane.ai/t/how-to-understand-tensor-observables-and-combined-measurements-from-the-perspective-of-quantum-mechanics/2023/3 "2022-07-13T08:32:43Z")
May I ask what is the meaning or mathematical difference between the tensor operation of the observation operator and the addition and subtraction of the observation operator?
---
### Author:  [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)
#### Post date: [July 14, 2022, 3:03am UTC](https://discuss.pennylane.ai/t/how-to-understand-tensor-observables-and-combined-measurements-from-the-perspective-of-quantum-mechanics/2023/4 "2022-07-14T03:03:54Z")
Hi @RX1, a tensor product is very different from addition and substraction. You can learn more about tensor products in [node I.11 of the Xanadu Quantum Codebook](https://codebook.xanadu.ai/I.11). The tensor product can be thought of as a special kind of multiplication between vectors, matrices, and vectors and matrices. The example in the codebook should bring much clarity to this concept.
Please let me know if this helps!