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Quantum Computational Supremacy


Last week Google and collaborators published a paper in which they claim to have achieved Quantum Supremacy , one of the major milestones in quantum computing. The idea of quantum supremacy is to use a programmable quantum device to perform a task that is out-of-reach for any classical computer Google claims to have solved a problem in seconds that would take tens of thousands of years on a state of the art supercomputer. The quantum supremacy experiment has been a long-standing milestone in the field of quantum computation, and as such, skepticism has arised; soon after publication of the article a group in IBM research has challenged the results 1.

Rather than joining in on the controversy of whether or not Google has really achieved quantum supremacy, I want to focus on some more basic questions: what is quantum supremacy, how does one demonstrate quantum supremacy and why is this such an important milestone?

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Net-Zero two-qubit gate published in Physical Review Letters

We have recently developed a new type of conditional-phase gate for transmon qubits providing several key improvements over standard flux-pulsing-based versions. The Net-Zero gate uses “leakage interference” to minimize leakage to non-computational states. The zero-average, bipolar shape of the pulse makes the gate robust to long timescale distortions in the flux control line and additionally provides an echo effect. We demonstrate a state-of-the-art conditional-phase gate of duration 40 ns achieving 99.1% fidelity and 0.1% leakage.

We invite you to check our paper at Physical Review Letters or ArXiv .


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Why turning a ket into a cat may or may not be a good idea

People often ask me what I do. There is a lot of things I can talk about: why is a quantum computer interesting or useful , or what do I actually do during my day. But quite often people end up asking a confused question about this curious story of an undead cat. In this blog post I will try to shed some light on this case as well as delve into the question of why we use these kind of stories.


Dead? Or alive? Or both?

When trying to understand a new theory we physicists love our thought experiments. We take some mathematical model of the world, change some parameters to see how it behaves and try to extract some rules of thumb or intuition from it.

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