Silq: A High-level Quantum Programming Language

1. Silq: A High-level Quantum Programming Language Benjamin Bichsel Maximilian Baader Timon Gehr Martin Vechev

2. Quantum Programming Languages Existing languages: Describe circuits Silq: Describes high-level operations Qiskit Quipper Reduce & simplify code Static safety / Prevent errors Q# ProjectQ QWire More intuitive semantics Safe automatic uncomputation LIQ𝑈𝑖|〉 QASM Forest … Downstream applications Physicality Source of icons: https://fontawesome.com

3. Quantum Programming Languages Comparison on Microsoft’s Q# coding contests, seehttps://silq.ethz.ch/comparison

4. Goals of this Lecture Discuss & compare languages Learn Silq’s language concepts Try out Silq Report issues Source of icons: https://fontawesome.com

5. Background (minimal)

6. Basic Features of Silq if x {     // controlled on x, y:=H(y); // apply H to y } y:=H(x); x:=H(x);

7. Grover’s Algorithm - Recap for all

8. Grover’s Algorithm in Silq

9. Grover’s Algorithm in Silq Time

10. Grover’s Algorithm in Silq

11. Grover’s Algorithm in Silq

12. Grover’s Algorithm in Silq

13. Grover’s Algorithm in Silq

14. Grover’s Algorithm in Silq

15. Grover’s Algorithm in Silq classical bijection

16. Grover’s Algorithm in Silq y:=f(x); qfree with

17. Grover’s Algorithm in Silq

18. Grover’s Algorithm in Silq

19. Automatic Uncomputation iff(cand){   phase(); } implicit measurement

20. Automatic Uncomputation const iff(cand){   phase(); } qfree

21. Live Coding

22. Summary of Type Annotations Documentation on http://silq.ethz.ch/documentation#/documentation/1_annotations const mfree qfree classical Source of icons: https://fontawesome.com

23. Downstream Applications Compilation Simulation Teaching Research Source of icons: https://fontawesome.com

24. Try Silq Yourself! Install Follow instructions on http://www.silq.ethz.ch/install Try examples Try to solve tasks / run solutions from http://www.silq.ethz.ch/examples Source of icons: https://fontawesome.com

25. Interested in Silq? Ask & Complain! Contact us! Bachelor/Master thesis Research projects PhD Benjamin Bichsel Max Baader Timon Gehr Prof. Martin Vechev (ETH Zürich) https://www.sri.inf.ethz.ch/ Source of icons: https://fontawesome.com

26. Invalid Programs From Live Coding • The following slides are here for completeness.

27. Preventing Errors- Use Consumed defuseConsumed(x:𝔹){ y := H(x); return(x,y); // undefined identifier x } defduplicateConst(constx:𝔹){ y := H(x); return(x,y); // no error }

28. Preventing Errors- Implicit Measurements defimplicitMeas[n:!ℕ](x:uint[n]){ y := x % 2; returny; } // parameter 'x' is not consumed defunconsumedConst[n:!ℕ](constx:uint[n]){ y := x % 2; returny; } // no error

29. Preventing Errors- Conditional Measurements defcondMeas(constc:𝔹,x:𝔹){ ifc{ x:= measure(x); } returnx; } // cannot call function 'measure[𝔹]' in 'mfree' context defclassCondMeas(constc:!𝔹,x:𝔹){ ifc{ x:= measure(x):𝔹; } returnx; } // no error

30. Preventing Errors- Reverse Measurements defrevMeas(){ returnreverse(measure); } // reversed function must be mfree

31. Preventing Errors- Invalid Uncomputation defnonConst(y:𝔹){ ifX(y) { // X consumes y phase(π); } } // non-'lifted' quantum expression must be consumed defsignFlipOf0(consty:𝔹){ ifX(y) { // X consumes a copy of y phase(π); } } // no error

32. Preventing Errors- Invalid Uncomputation defnonQfree(consty:𝔹,z:𝔹){ ifH(y) { z := X(z); } returnz; } // non-'lifted' quantum expression must be consumed