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Zaki Leghtas
1. Centre Automatique et Systèmes - Mines ParisTech
2. Laboratoire de Physique - Ecole Normale Supérieure de Paris
3. Quantic team - INRIA Paris
Superconducting circuits and Schrödinger’s cat
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Superconducting circuits
1 cm
𝑓 ≈ 5 GHz, 𝑄 ≈ 106−8
= S SINon-linear element
100 nm × 100 nm
High quality cavity
=
Josephson junction
Tfridge= 10 mK
arXiv: 1905.13641
QubitHarmonic oscillator
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Superconducting circuitsSuperconductivity Long lifetimeJosephson effect Large nonlinearityTelecom industry Precise qubit control
Semiconductor industry Complex architectures
Devoret and Schoelkopf, Science (2012) Rigetti computing arXiv:1712.05771
m
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How to protect quantum information against errors ?
Protected qubitOverhead " × 𝟏𝟎𝟑"
error
Physical qubit
My Goal: Reduce hardware overhead
Environment
quantum error correction
error
| ۧ1
| ۧ0
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𝑉
𝐼Q
The Cat-Qubit: a solution to scalability
Overhead: " × 𝟏𝟎"
Gates: rotations in phase-space
| ۧ1| ۧ0
High quality resonators
Nonlinear interactions
Gates
| ۧ1
Cat-Qubit: non local
Standard qubit: local
| ۧ0
exponentialsuppressionof errors
errors
Leghtas et al. Phys Rev Lett (2013), Mirrahimi, Leghtas et al. NJP (2014), Leghtas et al. Science (2015)
𝑉
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Preliminary data: exponential suppression of errors
𝟏 m𝒔
× 𝟒𝟎𝟎𝑇 error(𝜇𝑠)
Target: 1 second (× 106)
=
× 8 standard error correction by Google group: Nature (2015)
distance between states
25 μm
standardqubits
102
103
2 6
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Roadmap towards a scalable protected qubit
New: Guillaud, Mirrahimi arXiv:1904.09474 (2019)
2 qubit gate
3 qubit gateLinear repetion code
Building block for universal fault-tolerantquantum computation
1 qubit gate
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Summary
Build a protected qubit
Overcome hardware overhead for quantum error correction
MazyarMirrahimi
PierreRouchon
AlainSarlette
TakisKontos
MatthieuDelbecq
AudreyCottet
ZakiLeghtas
Quantum circuits: theory and experiments