Support for qubit loss #2567

swernli · 2025-06-26T23:40:21Z

This PR adds support for qubit loss to the QDK. In particular, it adds the following features:

Simulator with configured qubit loss will probabilistically "lose" qubits during application of noise (ie: any gates, measurements, or calls to ApplyIdleNoise), treating futher operations on that qubit as no-op.
Qubits that are lost return neither Zero nor One during measurement but a special Loss value that cannot be used in comparisons, triggering a runtime failure if it is.
Std.Diagnostics.ConfigureQubitLoss to configure the probability of qubit loss on any operation.
Std.Measurement.MResetZChecked which returns a tuple of (Result, Bool) by checking for qubit loss as part of measurement.
Loss checks generate into QIR by emitting the __quantum__rt__read_loss runtime function (may not be supported on all QIR targets).

Additional features:

Extension setting alongside Pauli noise for configuring loss probability during histogram generation
OpenQASM support for special measurement that returns loss bit, exposed via new "qdk.inc" special include
Python API for configuring loss probability on calls to qsharp.run
Samples for configuring and detecting loss

This PR adds support for qubit loss to the QDK. In particular, it adds the following features: - Simulator with configured qubit loss will probabilistically "lose" qubits during application of noise (ie: any gates, measurements, or calls to `ApplyIdleNoise`), treating futher operations on that qubit as no-op. - Qubits that are lost return neither `Zero` nor `One` during measurement but a special `Loss` value that cannot be used in comparisons, triggering a runtime failure if it is. - `Std.Diagnostics.ConfigureQubitLoss` to configure the probability of qubit loss on any operation. - `Std.Measurement.MResetZChecked` which returns a tuple of `(Result, Bool)` by checking for qubit loss as part of measurement. - Loss checks generate into QIR by emitting the `__quantum__rt__read_loss` runtime function (may not be supported on all QIR targets). TODO: - [ ] Extension setting alongside Pauli noise for configuring loss probability during histogram generation - [ ] OpenQASM support for special measurement that returns loss bit - [ ] Python API for configuring loss probability on calls to `qsharp.run` - [ ] Samples Fixes #2484, #2483

library/std/src/Std/Measurement.qs

source/compiler/qsc_eval/src/lib.rs

source/compiler/qsc_eval/src/intrinsic/tests.rs

github-actions · 2025-07-01T20:08:27Z

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library/std/src/Std/OpenQASM/Intrinsic.qs

github-actions · 2025-07-01T20:24:43Z

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github-actions · 2025-07-01T23:10:15Z

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github-actions · 2025-07-02T00:26:39Z

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github-actions · 2025-07-02T00:30:31Z

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github-actions · 2025-07-02T21:28:17Z

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source/compiler/qsc_eval/src/val.rs

source/npm/qsharp/src/compiler/compiler.ts

source/compiler/qsc_eval/src/backend.rs

github-actions · 2025-07-07T20:29:47Z

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github-actions · 2025-07-07T20:50:32Z

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source/compiler/qsc_eval/src/backend.rs

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github-actions · 2025-07-07T22:38:49Z

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github-actions · 2025-07-08T16:54:07Z

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github-actions · 2025-07-08T16:55:39Z

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github-actions · 2025-07-08T17:27:56Z

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samples/notebooks/noise.ipynb

source/compiler/qsc_eval/src/lib.rs

source/vscode/package.json

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swernli added 3 commits June 26, 2025 16:40

Add support for global qubit loss to affect histogram runs in extension

8ed42eb

Fix missing param

9b16914

DmitryVasilevsky reviewed Jun 30, 2025

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Add Python API for qubit loss

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swernli added 4 commits July 1, 2025 11:14

Add IsLossResult and additional tests

a23f014

Support checked measurement in OpenQASM

7039467

Fix tests

54b1d12

Add samples to noise notebook

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swernli marked this pull request as ready for review July 1, 2025 20:06

swernli requested review from billti, idavis, minestarks and ivanbasov as code owners July 1, 2025 20:06

swernli commented Jul 1, 2025

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Fix test spans

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Add sample of mresetz_checked usage to openqasm.ipynb

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swernli added 2 commits July 7, 2025 15:27

Adjust how Option is used in lossy sim

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Merge remote-tracking branch 'origin/main' into swernli/qubit-loss

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Fix formatting

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Doc string cleanup

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swernli enabled auto-merge July 9, 2025 17:10

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swernli deleted the swernli/qubit-loss branch July 9, 2025 17:48

Support for qubit loss #2567

Support for qubit loss #2567

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