Condensed Matter Seminar

Correlated states of interacting dopant spins on a silicon chip

Wednesday, 06 September 2017 12:00PM PDT
Condensed Matter Seminar
Joe Salfi
Joe Salfi School of Physics and Centre for Quantum Computation and Communication Technology (CQC2T). The University of New South Wales. Sydney, Australia.
Correlated states of interacting dopant spins on a silicon chip
Sep 06, 2017 at 12PM


The use of controllable quantum systems to emulate many-body Hamiltonians could make it possible to probe hitherto hidden properties of correlated quantum states and to realize quantum states not yet observed in nature [1]. While of exceptional interest, fermionic many-body systems with spin and charge degrees of freedom have been difficult to emulate to date, even in the few-particle limit. Optical lattices of cold fermions are difficult to cool to the quantum regime and lack local control and measurement [2], and conventional qubits have a large control overhead when simulating itinerant particles with spin and charge degrees of freedom [3].


Here we show that interacting dopant atoms in silicon can be used to simulate fermionic many-body systems while addressing the above difficulties. In particular, the Hubbard interaction strength can be tuned using different relative dopant positions, the effective temperature is appropriate for Hamiltonians of interest, and the spin and charge configurations of the system can be efficiently interrogated, experimentally. The temperature and interaction strength were determined from the spatially resolved spectrum of coupled spin eigen-states and interference of atomic orbitals, respectively [4], which were probed one electron at a time [5]. The spin and charge configuration was read out in a silicon transistor [6] with a gate electrode dispersively coupled to a radio frequency cavity [6] allowing with the closed two-atom system for spin-to-charge conversion [7]. This approach eliminates the need for single-electron transistors, and could reduce the overhead for experiments on multi-spin systems.

Towards the design of larger scale multi-spin fermionic Hubbard systems, we have recently demonstrated the ability to probe, one electron at a time [8] in a fully functioning device [9], the quantum states of the dopant atoms placed with atomic precision. The demonstrated capabilities open new pathways for quantum simulation using spins in silicon.



[1] Georgesu, Ashhab and Nori.  Reviews of Modern Physics 2014.
[2] Greif, Uehlinger, Jotzu, Tarruell and Esslinger. Science, 2013
[3] Barends, Lamata, Kelly, Garcia-Alvarez et al. Nature Communications 2015.
[4] JS, Mol, Rahman, Klimeck et al. Nature Communications 2016.
[5] JS, Mol, Rahman, Klimeck, Nature Materials 2014. Usman, Bocquel, JS, Voisin et al, Nature Nanotech 2016.
[6] van der Heijden, JS, Mol, Verduijn et al. Nano Letters 2014
[7] Colless, Mahoney, Hornibrook, Doherty, et al. Physical Review Letters (2013)
[8] van der Heijden Kobayashi, House, JS, et al, arXiv:1703.03538
[9] in preparation