Research funding in Korea

Earlier this month I had the pleasure of visiting former colleagues and collaborators in Korea. This was my first time delivering in-person seminars since covid and I had forgotten how invigorating and inspiring it is to present and discuss physics face-to-face.

One issue that I learned about during my trip was the lack of stability in science funding in Korea - research grants are typically reviewed (and funding levels adjusted) every year, and changes in government lead to dramatic shifts in funding priorities.

The Institute for Basic Science (IBS) was established in 2011 with the aim of providing a stable environment for carrying out long-term fundamental research.

After an initial 8-year grace period to give directors enough time to set up their centres, their performance is reviewed to determine whether funding should continue (see this 2020 perspective article for further background).

However, passing this review does give centres stability to continue to pursue their ambitious research goals. Subsequent performance reviews are planned every 3 years, with the potential for significant cuts in funding or even the entire centre shutting down.

A related issue is the puzzling combination of the centralisation of leadership while reducing the autonomy of the centre directors.

Presently tenure is limited to centre directors; if a director resigns, retires, or is hit by a bus the whole centre is shut down unless a suitable external replacement can be recruited. Meanwhile, team leaders on (on paper) tenure-track positions are not given the stability of tenure and the opportunity potentially replace directors reaching mandatory retirement age. Lasting institutions require strong base of staff at all different levels and clear avenues for career progression.

Despite directors being so essential to the continued operation of the research centres, government policy dictates that the hiring of research staff be delegated to an external committee. Moreover, candidates identities should be hidden from this committee, although publication lists can still be included in the "blinded" CVs! I understand this puzzling policy is not limited to IBS, but also applies to other government-funded research institutes.

It is remarkable that despite all these pressures and constraints researchers at IBS are still able to carry out world-class research!

Recently in glossy journals

Engineering topological states in atom-based semiconductor quantum dots

Very nice work implementing the SSH / Hubbard model using quantum dots, forming a platform for studying the interplay between band topology and quantum interactions. The accompanying press release from the spin-off company (Silicon Quantum Computing) is unfortunately pure hype, however. This is not a molecular simulation - it is an implementation of a model. A neat example of analogue quantum simulation, but this is not a general-purpose reprogrammable integrated quantum circuit. 

Quantum advantage in learning from experiments

 

An exponential quantum advantage for quantum machine learning! The fine print is that the advantage is for learning from quantum data.

An on-chip photonic deep neural network for image classification

 

A photonic neural network that uses optoelectronics to implement nonlinear activation functions. "Direct, clock-less processing of optical data eliminates analogue-to-digital conversion and the requirement for a large memory module, allowing faster and more energy efficient neural networks for the next generations of deep learning systems."

More on the academic job market

Another perspective on academic jobs was published in Science a few weeks ago: As professors struggle to recruit postdocs, calls for structural change in academia intensify.

Finding suitably-qualified postdocs to hire is a challenge, especially amidst competition from quantum startups that can afford to offer significantly higher salaries. 

Grant funding rules often prevent professors from offering competitive salaries.

Overhead fees claimed by universities are growing faster than postdoc salaries (NUS's overhead costs increased from 20% to 30% last year, if I recall correctly).

Something has to change.

ICOAM 2022 - live stream

The 6th International Conference on Optical Angular Momentum is running this week, featuring an impressive lineup of invited speakers including Sir Michael Berry (of geometric/Berry phase fame), who will be giving a public lecture on Friday.

The organisers have kindly provided a zoom livestream of the sessions so those who unable to attend in person can still watch the talks.

I will be giving my talk remotely on Wednesday morning. Here are my slides. My aim is to provide an accessible introduction to topological data analysis and offer some potentially-interesting directions for future research.

Unfortunately the review article we've been working on is not yet finished - I was hoping to have an arXiv link ready in time for my talk.

Steps towards a quantum advantage

Xanadu's latest results on Gaussian BosonSampling attracted quite a bit of media attention. Their essential breakthrough is to combine time multiplexing with number-resolved photon detectors to massively increase the number of modes and photon counts, pushing their device into a regime that seems to be intractable using classical computers. 

It is reassuring that one of the reviewers of the Nature paper was Sergio Boixo, who has also authored work on developing more efficient classical algorithms for spoofing Gaussian BosonSampling. Other advanced classical algorithms can spoof shallow circuits and measurements with too many photons per mode.

The Gaussian BosonSampling device is now accessible on AWS. The price per shot is (\$0.00020) is slightly more than half of that of the superconducting processors (\$0.00035). Note this is not a general-purpose system, which remains challenging to implement, as noted by the Xanadu team in their paper:

If one were to target a universal and programmable interferometer, with depth equal to the number of modes, that covers densely the set of unitary matrices, the exponential accumulation of loss would prohibit showing a quantum advantage. There are then two ways around this no-go result: one can either give up programmability and build an ultralow loss fixed static interferometer, ...., or give up universality while maintaining a high degree of multimode entanglement using long-ranged gates.

Despite the lack of universality, this does seem to be the first classically-intractable programmable quantum processor available for general use via the cloud!

 On a related note, last week Nature published a paper demonstrating repeated error correction, using 17 superconducting qubits to create a single logical qubit. Each error correction cycle took 1.1 us and succeeding with 97% probability (95% without post-selection). Quantum error correction experiments are still at a very early stage; this experiment (and most others) have not yet reached the "break-even" point where the logical qubit lifetime exceeds the lifetime of a single physical qubit.

The great resignation in physics

Yesterday Nature published a feature article asking "Has the great resignation hit academia?" The article mostly focuses on experiences of researchers in the humanities and life sciences, but they are equally relevant to physics. Some snippets:

"Grievances include a lack of support, increased workloads, ..., and salaries that have not kept up with cost of living." 

Unofficially, it seems that the salaries of fresh postdocs in Singapore have not increased significantly since 2015, despite rising costs of living, especially rent. Frustratingly, professors seem to be powerless to address this due to postdoc salaries being fixed by upper management or funding agency rules. Consequently it is very hard to attract and retain junior researchers.

"A 2018 study predicted that higher education would lose half to two-thirds of its academic workforce to retirement, career burnout or job dissatisfaction within five years."

"By May 2021, one in five academic jobs in Australia had been cut."

The sacking of Australian research staff is particularly galling given that upper management and administration seem to be doing better than ever. With the boom in quantum technologies many Australian researchers are realizing they can keep doing the same physics under much better working conditions in spin-off companies including Q-CTRL, Quantum Brilliance, Nomad Atomics, and Diraq.

ArXiv catchup

 Deadlines abound so I haven't been following arXiv postings that closely. Some papers of note from the last few weeks:

Dielectric Mie Voids: Confining Light in Air. The authors demonstrate a metasurface analogue of photonic crystal fibers. A neat idea that could enable ultra-low loss flat optics.

Beyond Barren Plateaus: Quantum Variational Algorithms Are Swamped With Traps. "We prove that a wide class of variational quantum models -- which are shallow, and exhibit no barren plateus -- have only a superpolynomially small fraction of local minima within any constant energy from the global minimum, rendering these models untrainable if no good initial guess of the optimal parameters is known." End-users beware: this work adds to evidence that variational quantum algorithms may not be scalable up to useful problem sizes.

Persistent homology analysis of a generalized Aubry-André-Harper model. Our own recent work on applying topological data analysis to study localization transitions in photonic lattices. What we found particularly exciting is that this is our first example of TDA discovering an unanticipated effect - the emergence of disorder-free eigenstates for certain model parameters.

Experimentally realized in situ backpropagation for deep learning in nanophotonic neural networks. Spoiler: the nonlinear activation functions are implemented digitally. Incorporating useful nonlinear optical response into integrated photonic neural networks while outperforming conventional electronic circuits is a big challenge. One promising potential solution is to employ measurement+based nonlinearities + feedforward.

Fabrication-Robust Silicon Photonic Devices in Standard Sub-Micron Silicon-on-Insulator Processes. With the continuing interest (and hype) in topological photonics it's important to keep in mind conventional non-topological approaches for designing photonic devices. For example, wider waveguides are more robust to fabrication imperfections, at the expense of being multimode. This is a problem, because waveguide bends will then induce coupling between the different guided modes, corrupting signals. Here the authors demonstrate how a clever choice of bending profile can suppress unwanted inter-modal coupling while not increasing the device footprint.

Breakdown of quantization in nonlinear Thouless pumping. Quantized adiabatic pumping of solitons attracted a lot of interest last year. This theoretical analysis shows how quantization can break down for moderate nonlinearity strengths due to the emergence of loops in the adiabatic energy spectrum, leading to dead-ends in the adiabatic path resulting in sudden non-adiabatic transitions of the soliton.