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CORDIS

Exotic superconducting CIrcuits to Probe and protect quantum States of light and mattEr

Project description

A new type of qubit for less resource-intensive quantum information protection

Quantum systems can exist in fragile states that are ultimately wiped out by interactions with the environment. Protecting such states is essential for the future of quantum computing. While quantum error correction does offer a solution, it requires vast resources. The EU-funded ECLIPSE project intends to tackle this problem by protecting quantum information in a new type of qubit with two crucial specificities. Firstly, encoding will take place in a single superconducting circuit resonator whose infinite dimensional Hilbert space can replace large registers of physical qubits. Secondly, this qubit will be radio-frequency-powered, continuously exchanging photons with a reservoir. The circuits developed will manipulate quantum states of light. This work could advance the protection of quantum information in future quantum systems.

Objective

Quantum systems can occupy peculiar states, such as superposition or entangled states. These states are intrinsically fragile and eventually get wiped out by inevitable interactions with the environment. Protecting quantum states against decoherence is a formidable and fundamental problem in physics, which is pivotal for the future of quantum computing. The theory of quantum error correction provides a solution, but its current envisioned implementations require daunting resources: a single bit of information is protected by encoding it across tens of thousands of physical qubits.

My proposal is to protect quantum information in an entirely new type of qubit with two key specificities. First, it will be encoded in a single superconducting circuit resonator whose infinite dimensional Hilbert space can replace large registers of physical qubits. Second, this qubit will be rf-powered, continuously exchanging photons with a reservoir. This approach challenges the intuition that a qubit must be isolated from its environment. Instead, the reservoir acts as a feedback loop which continuously and autonomously corrects against errors. This correction takes place at the level of the quantum hardware, and reduces the need for error syndrome measurements which are resource intensive.

The circuits I will develop manipulate quantum states of light, whose utility transcends the long term goal of quantum computing, and can readily be used to probe fundamental properties of matter. In mesoscopic physics where a large number of particles exhibit collective quantum phenomena, the measurement tools to characterize subtle quantum effects are often lacking. Here, I propose to measure the spin entanglement of a single Cooper pair, by coupling a superconductor to a circuit composed of microwave resonators and a carbon nanotube. The spin entanglement can be swapped into microwave photons, which can be detected by deploying the arsenal of quantum limited microwave measurement devices.

Host institution

ASSOCIATION POUR LA RECHERCHE ET LE DEVELOPPEMENT DES METHODES ET PROCESSUS INDUSTRIELS
Net EU contribution
€ 1 178 875,00
Address
BOULEVARD SAINT MICHEL 60
75272 Paris
France

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Region
Ile-de-France Ile-de-France Paris
Activity type
Research Organisations
Links
Total cost
€ 1 467 625,00

Beneficiaries (3)