WP1 Quantum processors & Simulators

Physics / Computer science / Industry
(Coordinator: T. Meunier) We will implement an elementary quantum algorithm on a solid-state platform. At the present time spin based or photonic based quantum computation are especially promising, building on the high level expertise in Grenoble (fig1)
WP1 Fig.1
Figure 1: Four potential building blocks for quantum processing and simulation in Grenoble. From left to right: spin qubit based on a CMOS quantum dot, quantum dot single photon source, superconducting circuit, molecular nanomagnet (artist view).
 

Spin based quantum computation

We will build small-scale quantum processors either with molecular magnets or electrons embedded in isotopically pure silicon (Si28). The LETI industry-grade CMOS nanofabrication facility offers the key assets to achieve scalability, reliability, integration of control and readout, low noise characteristics, etc. The project builds on our recent demonstration of coherently controlling individual spins in CMOS dots [BFT+15,MJK+16] and molecular magnets [VKR+12,TBB+15], where chemistry will allow us to tune the qubit's properties. Single-shot multi-qubit readout is necessary for error correction code. We will develop this through frequency-domain multiplexing, radio-frequency reflectometry, cryogenic low-noise amplification. By the end of the project, we aim to demonstrate this readout based error correction for a 5 qubits' architecture.
 

Photonic based quantum computation

A four-qubits photonic quantum processor exists [MLL+12], but scalability has been hindered by the low efficiency of the sources (based on parametric down-conversion) and detectors. We will address this through the integration of single photon sources [MCB+12] and superconducting single photon detectors [Sil] in a state-of-the-art Si photonic circuit [RBD+16]. We will demonstrate a CNOT gate based on photon coalescence on a beam splitter, followed by more complex photonic architectures. Original integrated quantum devices will emerge: high bit rate photon number generators, sources of NOON states for quantum sensing, and photon number resolving detectors. The commercial interest of these devices will be evaluated with the Dutch company Single Quantum [Sin], a key European player with established links to the Grenoble community. 
 

Quantum simulators

Arrays of superconducting qubits have recently been used to simulate the dynamics of chemical reactions and non-trivial quantum spin systems. We will develop two types of quantum simulators based on such qubits. The first aims to study quantum impurity problems, which are integral to the understanding of strongly correlated materials [BFB+14]. The second will simulate quantum spin liquids, considered as the next challenge in quantum magnetism.
Means 3 PhD grants+1full-time Chair of Excellence (with WP2). We shall encourage co-supervision, twinned PhDs (with computer scientists, see WP2), and industrial coaching (See Section 2 - Management). The Chair should allow fostering the collaboration between physicists and computer scientists, and create a new field of expertise in Grenoble.


 
Milestones
 
  • M1.1 (T0+24) Integrated photonic CNOT gate on a Si photonic chip
  • M1.2 (T0+48) Error correction on a 5 qubits' architecture

 
References
 
  • [BFT+15] Bertrand et al, PRL 115 096801 (2015)
  • [MJK+16] R. Maurand et al, arXiv:1605.07599;
  • [VKR+12] R. Vincent et al, Nature 488, 357 (2012);
  • [TBB+15] S. Thiele et al, Science 34401135 (2015)
  • [MLL+12] E. Martin-Lopez et al, Nature Photon 6, 773 (2012) ;
  • [MCB+12] M.Munsch et al, Phys. Rev. Lett. 108, 077405 (2012)
  • [Sil] see http://www-leti.cea.fr/en/How-to-collaborate/Focus-on-Technologies/Integrated-silicon-photonics;
  • [RBD+16] L. Redaelli et al, Supercon. Sci Tech 29, 065016 (2016) ;
  • [Sin] www.singlequantum.com;
  • [BFB+14] S. Bera et al, Physical Review B 89, 121108(R) (2014)
 

Published on January 23, 2018