This page presents the full list of technical problems that participants must solve using Entwine. Each task is designed to assess your ability to design, implement, and analyse fault-tolerant quantum circuits.
Intro Tutorials (optional):
- Lattice Surgery Basics as static PDF or as a PPTX with animations
- Entwine Basic Introduction Video
Task 1: Concatenated Repetition Code
- Consider a logical qubit encoded with the Repetition. Imagine if the physical data qubits of the QEC Code were instead replaced by logical qubits from the surface code — this creates a “concatenated” code. Use Entwine to design a sequence of lattice surgery operations to maintain error correction on this “concatenated code”.
- Concretely, let us consider a linear array of distance-3 surface code logical qubits used to encode a higher-level distance-3 logical qubit. Do some comparisons with a “regular” surface code qubit by choosing the appropriate code-distance of the “regular” surface code qubit. Use Entwine to obtain the Stim circuit for your choice. Alternatively, you may choose to use a “regular” surface code qubit that uses the same (or comparable) number of total physical qubits, and compare the number of errors that can be corrected by the “regular” surface code qubit. Write a Notebook, and run Stim simulations to compare the logical error rates of concatenated logical qubit and the regular one.
In the written report, include a code-snippet of the lattice surgery operations to complete part (a), and include logical error rate plots for part (b). You are welcome to include additional discussions to discuss any aspect of the concatenated code.
Participants’ reports and Jupyter Notebook are judged by the following criteria:
For part (a), having the correct set of operations that perform the requested task in the problem statement. Lattice surgery circuit sequence involves the least amount of logical qubits and additional physical qubits, as well as the shortest time to implement a single cycle of syndrome measurement.
For part (b), the ability to perform the “right” comparison is judged. Interesting conclusions/observations included in the report about the error-correcting ability of the two types of schemes are judged highly.
Task 2: Lattice Surgery compilation
Consider a simple circuit like in the figure below.
Use Entwine and write out a sequence of lattice surgery instructions that will implement this circuit at the logical level. Participants will earn a score based on the number of lattice surgery instructions, the number of logical qubits, the overall number of physical qubits used, as well the total number of time-steps to execute the circuit. If the participant used any other resource such as open-source tools or libraries, they should explain in their report how these resources were utilised.
Task 3: Concatenated Code, again (challenging!)
Consider a logical qubit encoded with the Surface Code. Imagine if the physical data qubits of the QEC Code were instead replaced by logical qubits from the surface code — this creates a “concatenated” code. Use Entwine to design a sequence of lattice surgery operations to maintain error correction on this “concatenated code”.
To complete this challenge, include a code-snippet of your lattice surgery operations in your written report.
You are welcome to include additional discussions to discuss any aspect of the concatenated code.
Participants’ reports and Jupyter Notebook are judged by the following criteria:
For part (a), lattice surgery circuit sequence involves the least amount of logical qubits and additional physical qubits, as well as the shortest time to implement a single cycle of syndrome measurement.
For part (b), the ability to perform the “right” comparison is judged. Interesting conclusions/observations included in the report about the error-correcting ability of the two types of schemes are judged highly.
How You’ll Be Scored
Each submission will be evaluated on a 100-point scale across the three technical tasks, plus up to 10 bonus craft points. Points can be awarded even for partial solutions. You do not need to complete all tasks to be eligible for a prize.
Task Point Weights
- Task 1 = 25 points
- Task 2 = 35 points
- Task 3 = 40 points
Specific Task Scoring Breakdown
Task 1.
- (a) Correctness of logical circuit. 15 points
- (b) Clarity of circuit structure through use of “layers” feature in Entwine. 2 points
- (c) Correctly identifying the right parameters of a Surface Code logical qubit to compare, and carrying out noise simulations correctly. 8 points.
Task 2.
- Accuracy of converting or “compiling” logical gate operations to lattice surgery steps. 20 points.
- Maximal Circuit compactness as measured by overall circuit depth and/or total number of lattice surgery operations, and total number of logical qubits utilised. 10 points
- Quality of explanation and annotation of methodology. 5 points.
Task 3.
- Correctness of logical circuit in implementing the concatenated Surface Code. 30 points
- Maximal Circuit compactness as measured by overall circuit depth and/or total number of lattice surgery operations, total number of physical qubits utilised. 10 points.
Craft Points
- Up to 10 bonus points for clarity, presentation, and insight
Partial Submissions
- Participants can submit any number of tasks (1, 2, or 3)
- Total score is the sum of points from submitted tasks + craft points
Scoring Formula
- Total Score = Σ(Task points) + Craft points
- Max possible score = 110 points
Tie-breaker Rules
- Higher score on Task 3
- Earlier submission timestamp (SGT)
- Final decision by the judging panel
Notes for All Submissions
- You may attempt any number of problems (1, 2, or 3)
- All designs must be created using Entwine
Refer to the Submission Page for detailed instructions.
If you have questions, contact us at [email protected].