### Emerging Technologies 2018 Session Listing

The program is subject to change in the weeks leading up to the conference. Check back here for the latest schedule, or follow us on Twitter for real-time notice of updates to the program.

###### Session C1: Quantum Computing and Photonics

Start Time: 13:30, Wednesday, May 09

Room: Cheakamus

Chaired by
Lukas Chrostowski, University of British Columbia (lukasc.ubc@gmail.com)

- 13:30 Marek Korkusinski, National Research Council
(Marek.Korkusinski@nrc-cnrc.gc.ca)
with S. Studenikin, A. Bogan, L. Gaudreau, G. Aers, P. Zawadzki, A. Sachrajda, L. Tracy, J. Reno and T. Hargett
Advances in the coherent control of holes in gated lateral quantum dots

Single holes localized in electrostatically tuneable quantum dot devices are explored as candidates for spin qubits. Here we study single-hole and two-hole hybrid spin-charge qubits in the presence of a strong spin-orbit interaction. For the single-hole regime we present results on the Landau-Zener-Stuckelberg (LZS) interferometry involving spin-conserving and spin-flip processes. LZS patterns evolve with microwave frequency from discrete (often referred to as PAT) at high frequencies to continuous LZS fringes at low frequencies. Taking LZS measurements at different magnetic fields we observe two separate sets of LZS fringes offset by the Zeeman energy.

The magnetic field dependence of the single hole spin relaxation time is measured, taking advantage of the latching technique we originally developed for electron spin qubits [1-2] and which is rapidly being adopted as a standard technique for high fidelity measurements.

Additionally, we extend LZS measurements to the two-hole case near the (02)-(11) transition and present results from LZS interferometry of the singlet-triplet spin qubit states.

[1] S. A. Studenikin

*et al*., Appl. Phys. Lett. 101, 233101 (2012). [2] J. D. Mason*et al*., Phys. Rev. B 92, 125434 (2015). - 13:50 Stephanie Simmons, Simon Fraser University
(s.simmons@sfu.ca)
A photonic link for donor spin qubits in silicon

Atomically identical donor spin qubits in silicon offer excellent native quantum properties, which match or outperform many qubit rivals. To scale up such systems it would be advantageous to connect silicon donor spin qubits in a cavity-QED architecture. A few proposals in this direction introduce strong electric dipole interactions to the otherwise largely isolated spin qubit ground state in order to couple to superconducting cavities, however these strategies have unknown coherence properties. Here I present an alternative approach, which uses the built-in strong electric dipole (optical) transitions of singly-ionized double donors in silicon. These donors, such as chalcogen donors S+, Se+, and Te+, have the same ground-state spin Hamiltonians as the extensively studied shallow donors, yet offer mid- gap binding energies and mid-IR optical access to excited orbital states. This photonic link is spin-selective which could be harnessed to measure and couple donor qubits using photonic cavity-QED at 4.2K.

- 14:10 Mark Eriksson, University of Wisconsin-Madison
(maeriksson@wisc.edu)
Controlling the coupling of silicon qubits to their noise environments

In order to achieve high-speed operation of semiconductor spin qubits, a strong control knob for qubit manipulation is essential. Increasingly, that control knob is a gate voltage coupling to the spin qubit through spin orbit coupling, which itself is often engineered in silicon through the use of micromagnets and the large magnetic field gradients they produce. I will discuss an alternative approach to coupling gate voltages to spins in silicon: using three electron spins in two quantum dots as a single qubit, a configuration called the quantum dot hybrid qubit (QDHQ) [1,2]. I will show recent results that demonstrate how changing the operating conditions for this qubit enables control of the coupling of the spin state to the noise environment [3]. Such tunability can be used, for example, to turn down the coupling to preserve coherence and to turn up the coupling when desired for qubit manipulation. The time scale for making such changes is very short, so that they can be implemented in real time during qubit operation.

[1] D. Kim,

*et al*., Nature 511, 70 (2014). [2] Dohun Kim,*et al*., npj Quant. Inf. 1, 15004 (2015). [3] B. Thorgrimsson,*et al*.,Ênpj Quant. Inf.Ê3, 32 (2017). - 14:30 Paul Barclay, University of Calgary
(pbarclay@ucalgary.ca)
Diamond optomechanical devices for quantum nanophotonics

- 14:50 Benoit Bertrand, CEA
(Benoit.BERTRAND@cea.fr)
with L. Hutin, R. Maurand, M. Urdampilleta, B. Jadot, H. Bohuslavskyi, L. Bourdet, Y.-M. Niquet, X. Jehl, S. Barraud,
C. Bäuerle, T. Meunier, M. Sanquer, S. De Franceschi and M. Vinet
Using Si CMOS technology as a platform for quantum computing

Spin qubits in silicon nanostructures are promising candidates towards the implementation of quantum information technologies, taking advantage of both their long coherence time — especially in isotopically purified 28Si [1] — and their potential for scalability. We present some recent progress and prospects in the use of fully-depleted silicon-on-insulator (FDSOI) technology to implement hole or electron spin qubits [2, 3]. The demonstration of foundry-compatibility is at the core of our approach as we study the functionality of qubits fabricated following a conventional transistor-like process flow. This is of particular relevance in terms of future up- scaling of qubit architectures as well as for the possibility of co-integration with classical Si CMOS control and readout circuitry.

[1] M. Veldhorst

*et al*., Nature 526, 410 (2015) [2] R. Maurand*et al*., Nat. Commun., 7, 13575 (2016) [3] A. Corna*et al*. arXiv:1708.02903 (2017) - 15:10 COFFEE BREAK
(Mt. Curie Foyer)
***************************************

- 15:30 Jonathan Baugh, University of Waterloo
(baugh@uwaterloo.ca)
A network architecture for silicon quantum computing

Several paths to a large scale, universal quantum computer have been proposed, though realization beyond the small scale (~50 qubits) remains a significant challenge. Superconducting qubits, semiconductor quantum dot and donor spin qubits, and topological qubits offer the exciting prospect for quantum analogues of the monolithic computer chip. In particular, quantum dots and donors in silicon have the advantage of a CMOS-compatible platform, which can exploit conventional foundry processes to fabricate the quantum device layer and integrate classical control circuitry via cryo-CMOS. In silicon, electron spin coherence times benefit from isotopic purification and a weak intrinsic spin-orbit coupling. Combining these CMOS-compatible qubits with a surface code architecture has been proposed for quantum dots and donor arrays. I will discuss some of the major challenges of such approaches, including density of wiring, integration of control electronics and multiplexing, noise and cross-talk, device yield and variability, and the need for advanced simulation tools to design and characterize real devices. I will then describe how a network architecture can provide an equivalent surface code functionality while reducing wiring density and isolating the qubits most critical to storing quantum information.

- 15:50 Philipp Niemann, DFKI
(Philipp.Niemann@dfki.de)
Compact representations for the design of quantum logic

For future quantum computers, going well beyond the size of present-day prototypes, the manual design of quantum circuits that realize a given (quantum) functionality on these devices is no longer an option. In order to keep up with the technological advances, methods need to be provided which, similar to the design and synthesis of conventional circuits, automatically generate a circuit description of the desired functionality. To this end, an efficient representation of the desired quantum functionality is of the essence. While straightforward representations are restricted due to their (exponentially) large matrix descriptions, we present a data-structure termed Quantum Multiple-Valued Decision Diagram (QMDD) — a means for compactly and efficiently representing and manipulating quantum logic. QMDDs employ a decomposition scheme that naturally models quantum systems. By this, they are able to take advantage of redundancies, thereby allowing a very compact representation of relevant quantum functionality composed of dozens of qubits. This provides the basis for the development of sophisticated design methods as will be illustrated by means of several exemplary applications in the field of quantum circuit synthesis and verification.

- 16:10 Ellen Schelew, Lumerical Inc.
(eschelew@lumerical.com)
Design, simulation and optimization of photonic components and systems for quantum applications

Photonic quantum technologies are in their infancy, and methodologies for component and system level modeling are still under development. Fortunately, classical integrated photonics and its supporting ecosystem are currently undergoing rapid growth and are leveraged for quantum applications. For component modeling, our shorter term efforts are focused on extracting useful quantum model parameters from purely classical, linear simulations. This approach uses mature numerical techniques for component design and is valid for many useful building blocks. Our longer term efforts involve more explicit coupling of quantum and classical behavior, however more work remains to achieve satisfactory self-consistency. Similarly, for system modeling, our initial efforts involve classical photonic circuit modeling combined with quantum analysis, which is often sufficient as these quantum circuits share many of the same components found in classical photonic circuits. Longer term efforts involve introducing new quantum compact models into classical circuit simulations.

- 16:30 Edoardo Charbon, EPFL, Technische Universität Delft
(e.charbon@tudelft.nl)
From SPADs for quantum sensing to cryo-CMOS interfaces for quantum computing

CMOS SPADs have appeared in 2003 and soon have risen to the status of image sensors with the creation of deep- submicron SPAD technology while the applications have literally exploded in the last three years, with the introduction of proximity sensing and portable telemeters. The current promise is that SPAD based sensors will be in every smartphone by 2018 and in every car by 2022. But SPAD technology was born for scientific applications and in scientific applications it will continue to innovate. For instance, super-resolution microscopy, time-of-flight PET, NIROT, FLIM, FRET are expected to become more and more accurate and less and less expensive thanks to the scalability of CMOS technologies. With the introduction of 3D CMOS IC technologies for SPADs, imagers will be more compact, with more advanced techniques and functionalities. Very recently, SPADs and in general CMOS circuits and systems have been proposed as an interface to quantum processors, due to their sensitivity and the capability of operating normally at cryogenic temperatures (cryo-CMOS). In this context, the emerging cryo-CMOS technology will be presented, with a technical and economic perspective, in view of the creation of scalable quantum computing platforms.

- 16:50 Jeff Young, University of British Columbia
(young@phas.ubc.ca)
Cavity-quantum-electrodynamic-based quantum information processing elements in silicon photonic circuits

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