
Design of a silicon quantum computer chip - breck
https://newsroom.unsw.edu.au/news/science-tech/complete-design-silicon-quantum-computer-chip-unveiled
======
ianopolous
The important bit: "The UNSW team has struck a A$83 million deal between UNSW,
Telstra, Commonwealth Bank and the Australian and New South Wales governments
to develop, by 2022, a 10-qubit prototype silicon quantum integrated circuit –
the first step in building the world’s first quantum computer in silicon."

So no, they haven't built a many-qubit general quantum computer.

~~~
vtomole
There has been some slow but noticeable progress in building quantum computers
using semiconductors. Researchers at Princeton were recently able to implement
a two-qubit quantum gate in silicon [0].

[0]:
[https://arxiv.org/pdf/1708.03530.pdf](https://arxiv.org/pdf/1708.03530.pdf)

~~~
huslage
I'm pretty sure that's not slow progress.

~~~
vtomole
It depends on what we mean by "slow progress". The physical implementation of
a quantum computer in silicon was proposed in 1998 [0] and a two-qubit gate
was recently performed on it. This is in contrast to the ion trap quantum
computer, where a two-qubit gate was proposed and performed in 1995 [1].

On the other hand, superconducting quantum computers followed the same road
that silicon is on right now. It took a couple of years for superconducting
qubits to be robust enough to perform universal quantum computation, but it's
progress has accelerated in the past couple of years. So this says nothing of
how fast silicon quantum computers will progress in the future.

[0]:
[https://en.wikipedia.org/wiki/Loss%E2%80%93DiVincenzo_quantu...](https://en.wikipedia.org/wiki/Loss%E2%80%93DiVincenzo_quantum_computer)

[1]:
[https://en.wikipedia.org/wiki/Trapped_ion_quantum_computer#H...](https://en.wikipedia.org/wiki/Trapped_ion_quantum_computer#History_of_trapped_ion_quantum_computing)

------
philipkglass
_Remarkable as they are, today’s computer chips cannot harness the quantum
effects needed to solve the really important problems that quantum computers
will. To solve problems that address major global challenges – like climate
change or complex diseases like cancer – it’s generally accepted we will need
millions of qubits working in tandem._

Are there non-classical algorithms with theoretical advantages for biological
or climate simulations? Or is this just more hype-nonsense courtesy of the
press office?

~~~
comicjk
In drug discovery, my field, we do a lot of quantum mechanics calculations,
which are formally exponential-scaling. Using a lot of approximations, we
reduce this to a polynomial, at the cost of accuracy. But a quantum computer
could do the original exponential problem with polynomial scaling
([https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2596249](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2596249)).
Quantum superiority for this problem would require a few hundred qubits, make
drug screening a lot more accurate, and make obsolete an enormous body of
theory devoted to classical approximations of this problem.

~~~
6nf
This is not my area but I understand that material sciences see the same kind
of potential for QCs - predicting how new alloys or ceramics will perform by
accurately simulating atomic interactions.

~~~
comicjk
Yes, that is true! During my PhD program I used the same methods to study
metalorganic solar cells.

If anything, fast quantum calculations would make an even bigger difference in
materials science than in drug discovery. That's because druglike molecules
have been studied a lot, so classical approximations (though limited) at least
exist.

~~~
j1vms
"Nature isn't classical, dammit, and if you want to make a simulation of
nature, you'd better make it quantum mechanical, and by golly it's a wonderful
problem, because it doesn't look so easy." \-- Richard Feynman

"Simulating Physics with Computers", International Journal of Theoretical
Physics, volume 21, 1982, p. 467-488, at p. 486 (final words) [0]

[0]
[https://en.wikiquote.org/wiki/Richard_Feynman#Quotes](https://en.wikiquote.org/wiki/Richard_Feynman#Quotes)

------
narrator
Does this require freezing the chip to near absolute zero like existing
designs?

~~~
vtomole
Yes it does. From the paper: "We assume that the complete structure is
maintained at cryogenic temperatures (∼1 K or less) inside an electron spin
resonance (ESR) system, which will be used to apply qubit control pulses."

~~~
aerovistae
Does that mean at all times (permanently, like whenever the chip is being
used) or just during manufacturing?

~~~
marcosdumay
That "using mostly standard silicon technology" phrase implies that cryogenic
temperatures are not needed during manufacturing, only during operation.

------
fauria
Previously on HN, Quantum Computing Explained:
[https://www.clerro.com/guide/580/quantum-computing-
explained](https://www.clerro.com/guide/580/quantum-computing-explained)

------
Ice_cream_suit
The actual article ( shorn of the breathless "oh my gosh" university PR
department hype ) is:

Silicon CMOS architecture for a spin-based quantum computer M. Veldhorst, H.
G. J. Eenink, C. H. Yang & A. S. Dzurak Nature Communications 8, Article
number: 1766 (2017) doi:10.1038/s41467-017-01905-6

It can be found free at:
[https://www.nature.com/articles/s41467-017-01905-6](https://www.nature.com/articles/s41467-017-01905-6)

ABSTRACT: "Recent advances in quantum error correction codes for fault-
tolerant quantum computing and physical realizations of high-fidelity qubits
in multiple platforms give promise for the construction of a quantum computer
based on millions of interacting qubits.

However, the classical-quantum interface remains a nascent field of
exploration. Here, we propose an architecture for a silicon-based quantum
computer processor based on complementary metal-oxide-semiconductor (CMOS)
technology. We show how a transistor-based control circuit together with
charge-storage electrodes can be used to operate a dense and scalable two-
dimensional qubit system.

The qubits are defined by the spin state of a single electron confined in
quantum dots, coupled via exchange interactions, controlled using a microwave
cavity, and measured via gate-based dispersive readout.

We implement a spin qubit surface code, showing the prospects for universal
quantum computation. We discuss the challenges and focus areas that need to be
addressed, providing a path for large-scale quantum computing."

------
stevemk14ebr
Does anyone know if this is just marketing or if they've actually solved the
technical problem. If they have solved it, what's the ETA (months, years,
decades)?

~~~
wbhart
I am not an expert, but my assessment is that it's pure marketing. They talk
about needing millions of qubits to do useful computations. This is flat out
false. Thousands will already solve interesting problems that no classical
computer can currently solve, e.g. factoring RSA moduli. They also say that
many qubits operating together will be required to build a practical quantum
computer (true), and that their technology allows this (false). The problems
involved in maintaining coherence and correcting errors, at reasonable
operating temperatures do not boil down to how to fit multiple qubits on a
silicon wafer. This is like saying a new process for manufacturing nuts and
bolts will allow the construction of Boeing 747's. The paper may contain more
sensible statements, but as usual, the press release is probably nonsense.

~~~
fudged71
When I took a course on quantum computing in 2007 with a standford prof, he
said that things would get interesting after we get to 128 qubits :)

~~~
eberkund
That's a very specific number, do you know what the relevance of 128 is?

~~~
garmaine
He is probably referencing the 128 bit security threshold most crypto systems
seek to achieve. However this doesn’t really line up with the number of qubits
needed to break said crypto, which is typically much larger (thousands of
qubits, plus error correction to survive millions of operations).

~~~
garmaine
Edit: less than a doubling. Eg from 128 to 192 or from 256 to 384. I meant to
say a doubling is sufficient.

------
naskwo
Given the order-of-magnitude increase in speed
([https://www.theregister.co.uk/2016/04/18/d_wave_demystifies_...](https://www.theregister.co.uk/2016/04/18/d_wave_demystifies_...))
combined with the assumption that the price of these chips will go down as
commercialization becomes more viable, isn't it naive to even consider the
viability of cryptocurrency? I mean, if the core underlying value of this
"asset class" is the fact that there is a scarcity of numbers (like collector
baseball cards) combined with ease and anonymity of transactions (like
diamonds), then unlimited computing power will demolish the value of
cryptocurrencies as much as alchemy would diminish the value of Au.

~~~
flignats
There are several quantum resistant crypto currencies. I.e. IOTA

~~~
banderman
Can you please explain what makes it quantum resistant?

~~~
nine_k
Not all crypto becomes easy to crack with a quantum computer:
[https://en.wikipedia.org/wiki/Post-
quantum_cryptography](https://en.wikipedia.org/wiki/Post-quantum_cryptography)

With its use, the scarcity of numbers remain, that is, finding a clash that
would allow to forge a transaction stays infeasible, and mining stays hard.

BTW while mining is so important with Bitcoin and Etherium, it's not a
necessary part of a cryptocurrency. Mining is an incentive to keep doing
blockchain validation. Some currencies exist without it (e.g. NXT).

~~~
bdamm
To date the only practical replacements for RSA and EC achieve key derivation
but not signatures. Without signatures we're not really 'complete' since
certificates are hard to do with only key derivation.

Post-quantum cryptograph research is a very active area right now. If these
researchers do not find a practical signature algorithm, PKI as we know it
will change very significantly.

Ironically, blockchains might elevate in importance as a result, since the
evolving blockchain is a useful construct for quantum resistance. It has
cryptographic agility built in.

------
tagrun
Before anyone gets excited about getting a practical quantum computer soon, it
should be emphasized that while they're experimentalists, this news is only
about a design they have in mind to use with their SiMOS quantum dots. There's
a gap between that design and the status quo of their physical quantum gates
in their lab.

Their gates (both single and two qubit gates) are slow and their fidelities
currently are below the threshold required for surface codes. There're also
big questions about the readout fidelities (which is way low at the moment)
and suppressing crosstalk.

That being said, quantum dots in Si/SiGE and SiMOS is a very exciting field
these days.

------
turndown
Are there any good introductory pieces on quantum computing? I feel like I've
heard so much about the subject, yet have not found a good paper to read that
outlines the essential concepts/topics involved with it.

~~~
sharp11
Michael Nielsen also has a really nice, accessible series of intro videos:
[http://michaelnielsen.org/blog/quantum-computing-for-the-
det...](http://michaelnielsen.org/blog/quantum-computing-for-the-determined/)

------
IndrekR
I think it is worth to mention that their team at UNSW is hiring and has PhD
scholarships available. About 30 positions are open.

I am not affiliated them, but noticed the listings at
[http://www.cqc2t.org/employment](http://www.cqc2t.org/employment)

~~~
Gatsky
This is interesting - they plan to deliver a revolutionary device in 5 years
and are about to hire 30 new people. Is that really feasible? I suppose the
funding cycles mean you have no choice, because it is not possible to maintain
a large dedicated research workforce for prolonged periods.

------
maga_2020
would somebody be able to compare this design with Microsoft's topological
qubit design? which one has better unwanted interference/error correction
potential, also are there any foundational operations that one design could
do, but the other will not be able to ?

------
cyberpunk0
Why silicon and not something like graphene

------
ct520
uh so what does this mean?

~~~
mtgx
That we could have quantum computing "accelerators" in our computers and maybe
even smartphones by 2030, just like we're starting to see machine learning
accelerators now (or GPUs for graphics processing in the 90's).

~~~
matte_black
So what kind of stuff can we do with that?

~~~
jcoffland
Nothing significant until we have many more qubits. With 128 qubits you could
crack 128 bit RSA encryption in a few mins.

~~~
api
I've thought for a long time that this explains why the NSA is recording so
much encrypted data. When QCs are available they will be able to decrypt all
the things. Imagine what they'll learn.

~~~
qubex
That’s a bit conspiracy-theorist-ish but unfortunately in the present climate
and given that has transpired from the Snowden leaks not at all implausible.

Either they have made a breakthrough in number theory that allows
factorisation over finite fields, or they have a quantum computer already, or
they are banking on having one soon. In any case, storage is so cheap that it
makes sense to just record the traffic (which is useful for sigint anyway) and
refer back to it “if and when”.

Of course, much of what we consider “public-key encrypted” traffic is actually
encrypted with a symmetric cipher whose encryption is impervious to Shor’s
Algorithm… it is the key-exchange process that _really_ uses the textbook
public-key encryption algorithms. So much of the traffic is technically
impervious to whatever advances they have made, but of course once you have
captured the key-exchange “handshake” that sets up the session and exchanges
the symmetric cipher keys, you’re all set to retrieve the plaintext from the
intercept.

There are public-key algorithms (particularly those based on lattices) that we
currently hold to be secure against attack by quantum computers. I am
surprised these are not seeing more adoption amongst the “ _enlightened
paranoid cypherpunk elite_ ”. Here is a primer on such “ _post-quantum
cryptography_ ” approaches, courtesy of the good folks at Wikipedia:
[https://en.wikipedia.org/wiki/Post-
quantum_cryptography](https://en.wikipedia.org/wiki/Post-quantum_cryptography)

~~~
api
In the process they'd get key exchanges too and it's easy to correlate
traffic.

I thought it was a really straightforward obvious idea. I'd do it if I were
them and had such deep pockets.

QC is clearly coming. Lots of news lately.

~~~
qubex
I was agreeing with you, of course if they have intercepted all traffic they
have both public-key encryption key exchange and the resulting symmetrically
encrypted traffic and that they could correlate it... I’m sorry if I was a bit
longwinded and pedantic in my reply, I didn’t realise I was talking to virtual
Hacker News nobility (with ten times the karma I do!).

~~~
api
Hacker News nobility is a dubious title haha.

Btw on post quantum crypto: the problem is that most of it has not yet had
enough conventional cryptanalysis. Makes no sense to use an algorithm immune
to quantum speedup if it's conventionally vulnerable.

~~~
qubex
Yeah I know, I’m no expert, but I studied applied mathematics.

------
visarga
I, too, have a complete design for the warp engine in my basement.

------
3chelon
About the only ting i know about quantum computing is it will make current
encryption techniques redundant. Is anyone thinking seriously about what that
will mean for global e-commerce? There will be a point in time when these
machines are not affordable on the mass market, but affordable by governments.
At that point, presumably, we are all going to be pwned?

~~~
sebular
I think you mean "obsolete" and not "redundant" but yes, the common asymmetric
encryption methods used for things like HTTPS are trivially cracked with a
powerful enough quantum computer.

The good news is that people have been anticipating this for a while, and
there's a lot of study in the field of post-quantum encryption. From what I
understand, people have come up with techniques that work (meaning nobody's
discovered a reason why they wouldn't work).

The bad news is that this does nothing for the data that we're currently
encrypting. There's nothing to stop someone from storing today's encrypted web
traffic and decoding it in the future when working quantum computers are
capable.

Thanks to Edward Snowden and others, we know that the US government is already
hoarding and sifting through data, so I have no doubt that there are plenty of
agencies planning on doing this exact thing.

