Bosonic examples

[elib20]

Context: The bosonic backend is a new backend for simulating states as a linear combination of Gaussian functions in phase space.

Description of the Change:

• Adds the marginal method to the BaseBosonicState class. This can be used to calculate marginal distributions along a given quadrature.
• Adds examples of calculations used the bosonic backend: homodyne sampling for GKP and cat states, measurement-based squeezing on vaccum, realistic phase gate applied to a GKP state
• Updates the changelog to reflect the new backend.

Benefits:

Possible Drawbacks:

Related GitHub Issues:

[codecov]

Codecov Report

Merging #549 (910f9c1) into master (1ff88e7) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #549   +/-   ##
=======================================
  Coverage   98.23%   98.23%           
=======================================
  Files          76       76           
  Lines        8384     8397   +13     
=======================================
+ Hits         8236     8249   +13     
  Misses        148      148           

Impacted Files	Coverage Δ
strawberryfields/backends/states.py	99.83% <100.00%> (+<0.01%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 1ff88e7...910f9c1. Read the comment docs.

[thisac]

Great job with all of this! 🚀

Just had a few comments on the changelog, and some questions/comments on the examples. Are those meant to be advertised to the users as tutorials? In that case it would probably be nice to flesh them out a bit with more detailed comments and explanations. 🤔

[elib20]

Great job with all of this! 🚀

Just had a few comments on the changelog, and some questions/comments on the examples. Are those meant to be advertised to the users as tutorials? In that case it would probably be nice to flesh them out a bit with more detailed comments and explanations. 🤔

Sorry for the confusion created by the branch title! This is not the official tutorial (Nico is working on that). These are just examples that will be explained more in the tutorial, and I thought they would fit in well in the examples folder.

[josh146]

Awesome work 🎉 It's really huge seeing the changes listed in the changelog!

[thisac]

Thanks for addressing my comments @elib20! 💯

Just had a very small one on the changelog links, but otherwise it looks great.