# PennyLane Challenges **URL:** https://discuss.pennylane.ai/c/pennylane-challenges/24.md [Latest](https://discuss.pennylane.ai/latest.md) · [Categories](https://discuss.pennylane.ai/categories.md) --- ## [About the PennyLane Challenges category](https://discuss.pennylane.ai/t/about-the-pennylane-challenges-category/4489)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 0
Use this category for questions about the PennyLane Challenges! You can find them at pennylane.ai/challenges. Please do your best to solve them on your own, but if you’re really stuck or if you’ve noticed a bug we’ll do… --- ## [The Super Parameter: solutions are being evaluated incorrectly](https://discuss.pennylane.ai/t/the-super-parameter-solutions-are-being-evaluated-incorrectly/9525)
**Author:** [@justin6626](https://discuss.pennylane.ai/u/justin6626)\ **Replies:** 0\ **Last updated:** [September 27, 2026, 4:30pm UTC](https://discuss.pennylane.ai/t/the-super-parameter-solutions-are-being-evaluated-incorrectly/9525 "2026-09-27T16:30:51Z")
I have been working on the Super Parameter challenge, and one of my submissions was evaluated as correct even though I know that it was wrong. I hadn’t finished my solution yet, but I clicked submit in order to save what… --- ## [PennyLane Challenge: Revisiting Schrodinger's cat](https://discuss.pennylane.ai/t/pennylane-challenge-revisiting-schrodingers-cat/4509)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 5\ **Last updated:** [July 3, 2026, 1:30am UTC](https://discuss.pennylane.ai/t/pennylane-challenge-revisiting-schrodingers-cat/4509 "2026-07-03T01:30:26Z")
Use this topic to ask your questions about the PennyLane Challenge: Revisiting Schrodinger’s cat. --- ## [PennyLane x unitaryHACK2026 challenge](https://discuss.pennylane.ai/t/pennylane-x-unitaryhack2026-challenge/9345)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 0\ **Last updated:** [May 26, 2026, 4:01am UTC](https://discuss.pennylane.ai/t/pennylane-x-unitaryhack2026-challenge/9345 "2026-05-26T04:01:00Z")
Use this topic to ask your questions about the PennyLane x unitaryHACK2026 challenge. You can earn an exclusive, time-limited badge for completing it! --- ## [PennyLane v0.45 Challenge: Resource Estimation](https://discuss.pennylane.ai/t/pennylane-v0-45-challenge-resource-estimation/9337)
**Author:** [@dren](https://discuss.pennylane.ai/u/dren)\ **Replies:** 0\ **Last updated:** [May 12, 2026, 4:40pm UTC](https://discuss.pennylane.ai/t/pennylane-v0-45-challenge-resource-estimation/9337 "2026-05-12T16:40:55Z")
Use this topic to ask your questions about the PennyLane Challenge: Introduction to Resource Estimation. You can earn a badge for completing it! --- ## [Certificate Challenge: Introduction to PennyLane](https://discuss.pennylane.ai/t/certificate-challenge-introduction-to-pennylane/4494)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 52\ **Last updated:** [September 5, 2025, 8:52pm UTC](https://discuss.pennylane.ai/t/certificate-challenge-introduction-to-pennylane/4494 "2025-09-05T20:52:37Z")
Use this topic to ask your questions about the Certificate Challenge: Introduction to PennyLane. --- ## [QHack 2023 challenge: The Super Parameter](https://discuss.pennylane.ai/t/qhack-2023-challenge-the-super-parameter/4715)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 8\ **Last updated:** [August 14, 2025, 5:36pm UTC](https://discuss.pennylane.ai/t/qhack-2023-challenge-the-super-parameter/4715 "2025-08-14T17:36:27Z")
Use this topic to ask your questions about the QHack 2023 challenge: The Super Parameter --- ## [PennyLane Challenge: Universality of single-qubit gates](https://discuss.pennylane.ai/t/pennylane-challenge-universality-of-single-qubit-gates/4505)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 15\ **Last updated:** [August 11, 2025, 7:49pm UTC](https://discuss.pennylane.ai/t/pennylane-challenge-universality-of-single-qubit-gates/4505 "2025-08-11T19:49:57Z")
Use this topic to ask your questions about the PennyLane Challenge: Universality of single-qubit gates. --- ## [A typo in A Simple Trotterization](https://discuss.pennylane.ai/t/a-typo-in-a-simple-trotterization/8775)
**Author:** [@mack.attack](https://discuss.pennylane.ai/u/mack.attack)\ **Replies:** 1\ **Last updated:** [July 18, 2025, 2:28pm UTC](https://discuss.pennylane.ai/t/a-typo-in-a-simple-trotterization/8775 "2025-07-18T14:28:09Z")
Just writing to request a change regarding incorrect commenting. While completing the Beginner challenge “A simple trotterization,” I noticed that on Line 13, it says “The coefficient of the YY term in the Hamiltonian, … --- ## [QHack 2023 challenge: A Noisy Heisenberg Model](https://discuss.pennylane.ai/t/qhack-2023-challenge-a-noisy-heisenberg-model/4719)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 8\ **Last updated:** [March 12, 2025, 3:19pm UTC](https://discuss.pennylane.ai/t/qhack-2023-challenge-a-noisy-heisenberg-model/4719 "2025-03-12T15:19:08Z")
Use this topic to ask your questions about the QHack 2023 challenge: A Noisy Heisenberg Model --- ## [version question](https://discuss.pennylane.ai/t/version-question/7782)
**Author:** [@w2534765383](https://discuss.pennylane.ai/u/w2534765383)\ **Replies:** 1\ **Last updated:** [January 9, 2025, 9:20pm UTC](https://discuss.pennylane.ai/t/version-question/7782 "2025-01-09T21:20:46Z")
model.params = opt.step(cost, approx=‘block-diag’) Here is the error message:： ValueError: The objective function must be encoded as a single QNode for the natural gradient to be automatically computed. Otherwise, met… --- ## [PennyLane Challenge: Returning expectation values](https://discuss.pennylane.ai/t/pennylane-challenge-returning-expectation-values/4496)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 5\ **Last updated:** [November 15, 2024, 7:17pm UTC](https://discuss.pennylane.ai/t/pennylane-challenge-returning-expectation-values/4496 "2024-11-15T19:17:39Z")
Use this topic to ask your questions about the PennyLane Challenge: Returning expectation values. --- ## [Pennylane device preprocess error for certain observables in V 0.38.0](https://discuss.pennylane.ai/t/pennylane-device-preprocess-error-for-certain-observables-in-v-0-38-0/5342)
**Author:** [@spacetraveler](https://discuss.pennylane.ai/u/spacetraveler)\ **Replies:** 3\ **Last updated:** [October 10, 2024, 12:31am UTC](https://discuss.pennylane.ai/t/pennylane-device-preprocess-error-for-certain-observables-in-v-0-38-0/5342 "2024-10-10T00:31:14Z")
Hi Pennylane Team, While working to solve the Secrets in Spacetime Challenge, I found some interesting behavior for measurement functions like expval() and counts() in Version 0.38.0. I was playing around with some obse… --- ## [PennyLane Challenge: The oracle of the exact distance](https://discuss.pennylane.ai/t/pennylane-challenge-the-oracle-of-the-exact-distance/4512)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 2\ **Last updated:** [September 6, 2024, 12:35am UTC](https://discuss.pennylane.ai/t/pennylane-challenge-the-oracle-of-the-exact-distance/4512 "2024-09-06T00:35:32Z")
Use this topic to ask your questions about the PennyLane Challenge: The oracle of the exact distance. --- ## [QHack 2023 challenge: A Pauli-Worded Problem](https://discuss.pennylane.ai/t/qhack-2023-challenge-a-pauli-worded-problem/4716)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 2\ **Last updated:** [August 21, 2024, 4:10am UTC](https://discuss.pennylane.ai/t/qhack-2023-challenge-a-pauli-worded-problem/4716 "2024-08-21T04:10:48Z")
Use this topic to ask your questions about the QHack 2023 challenge: A Pauli-Worded Problem --- ## [PennyLane Challenge: Quantum state discrimination](https://discuss.pennylane.ai/t/pennylane-challenge-quantum-state-discrimination/4507)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 2\ **Last updated:** [August 21, 2024, 4:04am UTC](https://discuss.pennylane.ai/t/pennylane-challenge-quantum-state-discrimination/4507 "2024-08-21T04:04:16Z")
Use this topic to ask your questions about the PennyLane Challenge: Quantum state discrimination. --- ## [Pennylane Coding Challenge : Universality of single-qubit gates](https://discuss.pennylane.ai/t/pennylane-coding-challenge-universality-of-single-qubit-gates/3506)
**Author:** [@Monit\_Sharma](https://discuss.pennylane.ai/u/Monit_Sharma)\ **Replies:** 19\ **Last updated:** [August 21, 2024, 3:35am UTC](https://discuss.pennylane.ai/t/pennylane-coding-challenge-universality-of-single-qubit-gates/3506 "2024-08-21T03:35:10Z")
I am solving the pennylane coding challenge, and I’m stuck with this problem. This is what my code looks like for the said problem. np.random.seed(1967) def get\_matrix(params): """ Args: - params (array… --- ## [QHack 2023 challenge: Mid-Circuit Measurements](https://discuss.pennylane.ai/t/qhack-2023-challenge-mid-circuit-measurements/4709)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 2\ **Last updated:** [August 16, 2024, 9:06pm UTC](https://discuss.pennylane.ai/t/qhack-2023-challenge-mid-circuit-measurements/4709 "2024-08-16T21:06:44Z")
Use this topic to ask your questions about the QHack 2023 challenge: Mid-Circuit Measurements --- ## [Qml.expval is returning Tensor object](https://discuss.pennylane.ai/t/qml-expval-is-returning-tensor-object/4885)
**Author:** [@phani.bharath](https://discuss.pennylane.ai/u/phani.bharath)\ **Replies:** 3\ **Last updated:** [July 18, 2024, 2:32am UTC](https://discuss.pennylane.ai/t/qml-expval-is-returning-tensor-object/4885 "2024-07-18T02:32:20Z")
I created a Qnode with below code def circuit(params, hamiltonian): parameters = params.reshape((LAYERS, WIRES, 3)) qml.templates.StronglyEntanglingLayers(parameters, wires=range(WIRES)) return qml.expval(qml.Hermiti… --- ## [QHack 2023 challenge: Introduction to LCUs](https://discuss.pennylane.ai/t/qhack-2023-challenge-introduction-to-lcus/4713)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 4\ **Last updated:** [July 3, 2024, 8:29pm UTC](https://discuss.pennylane.ai/t/qhack-2023-challenge-introduction-to-lcus/4713 "2024-07-03T20:29:14Z")
Use this topic to ask your questions about the QHack 2023 challenge: Introduction to LCUs --- ## [QHack 2023 challenge: Hi, Hydrogen!](https://discuss.pennylane.ai/t/qhack-2023-challenge-hi-hydrogen/4712)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 4\ **Last updated:** [June 24, 2024, 6:46pm UTC](https://discuss.pennylane.ai/t/qhack-2023-challenge-hi-hydrogen/4712 "2024-06-24T18:46:06Z")
Use this topic to ask your questions about the QHack 2023 challenge: Hi, Hydrogen! --- ## [QHack 2023 challenge: A Shor Thing](https://discuss.pennylane.ai/t/qhack-2023-challenge-a-shor-thing/4710)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 0\ **Last updated:** [June 17, 2024, 12:00pm UTC](https://discuss.pennylane.ai/t/qhack-2023-challenge-a-shor-thing/4710 "2024-06-17T12:00:29Z")
Use this topic to ask your questions about the QHack 2023 challenge: A Shor Thing. --- ## [What is this params list shape ? ( 4x4 ?)](https://discuss.pennylane.ai/t/what-is-this-params-list-shape-4x4/4783)
**Author:** [@Md\_Zubair](https://discuss.pennylane.ai/u/Md_Zubair)\ **Replies:** 1\ **Last updated:** [June 21, 2024, 8:18pm UTC](https://discuss.pennylane.ai/t/what-is-this-params-list-shape-4x4/4783 "2024-06-21T20:18:17Z")
here, isn’t it supposed to be 4x4, or something else ? i am converting it into numpy array, to applied tolist, but not getting desired output --- ## [QHack 2023 challenge: Undo that Computation](https://discuss.pennylane.ai/t/qhack-2023-challenge-undo-that-computation/4711)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 0\ **Last updated:** [June 17, 2024, 12:00pm UTC](https://discuss.pennylane.ai/t/qhack-2023-challenge-undo-that-computation/4711 "2024-06-17T12:00:30Z")
Use this topic to ask your questions about the QHack 2023 challenge: Undo that Computation --- ## [QHack 2023 challenge: Ising Uprising](https://discuss.pennylane.ai/t/qhack-2023-challenge-ising-uprising/4717)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 0\ **Last updated:** [June 17, 2024, 12:00pm UTC](https://discuss.pennylane.ai/t/qhack-2023-challenge-ising-uprising/4717 "2024-06-17T12:00:30Z")
Use this topic to ask your questions about the QHack 2023 challenge: Ising Uprising --- ## [QHack 2023 challenge: The Lazy Colleague](https://discuss.pennylane.ai/t/qhack-2023-challenge-the-lazy-colleague/4722)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 0\ **Last updated:** [June 17, 2024, 12:00pm UTC](https://discuss.pennylane.ai/t/qhack-2023-challenge-the-lazy-colleague/4722 "2024-06-17T12:00:29Z")
Use this topic to ask your questions about the QHack 2023 challenge: The Lazy Colleague --- ## [QHack 2023 challenge: Changing Qubits](https://discuss.pennylane.ai/t/qhack-2023-challenge-changing-qubits/4720)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 0\ **Last updated:** [June 17, 2024, 12:00pm UTC](https://discuss.pennylane.ai/t/qhack-2023-challenge-changing-qubits/4720 "2024-06-17T12:00:29Z")
Use this topic to ask your questions about the QHack 2023 challenge: Changing Qubits --- ## [QHack 2023 challenge: Don't Hit the Ground](https://discuss.pennylane.ai/t/qhack-2023-challenge-dont-hit-the-ground/4718)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 0\ **Last updated:** [June 17, 2024, 12:00pm UTC](https://discuss.pennylane.ai/t/qhack-2023-challenge-dont-hit-the-ground/4718 "2024-06-17T12:00:29Z")
Use this topic to ask your questions about the QHack 2023 challenge: Don’t Hit the Ground --- ## [QHack 2023 challenge: Secrets in Spacetime](https://discuss.pennylane.ai/t/qhack-2023-challenge-secrets-in-spacetime/4714)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 0\ **Last updated:** [June 17, 2024, 12:00pm UTC](https://discuss.pennylane.ai/t/qhack-2023-challenge-secrets-in-spacetime/4714 "2024-06-17T12:00:29Z")
Use this topic to ask your questions about the QHack 2023 challenge: Secrets in Spacetime --- ## [QHack 2023 challenge: An Itch to Switch](https://discuss.pennylane.ai/t/qhack-2023-challenge-an-itch-to-switch/4721)
**Author:** [@CatalinaAlbornoz](https://discuss.pennylane.ai/u/CatalinaAlbornoz)\ **Replies:** 0\ **Last updated:** [June 17, 2024, 12:00pm UTC](https://discuss.pennylane.ai/t/qhack-2023-challenge-an-itch-to-switch/4721 "2024-06-17T12:00:29Z")
Use this topic to ask your questions about the QHack 2023 challenge: An Itch to Switch [Next page](https://discuss.pennylane.ai/c/pennylane-challenges/24.md?page=1)