2
$\begingroup$

I am reading a company's (Archer Materials) press release on their progress towards building a quantum computing chip and I have a question about how a certain statements are phrased:

Archer’s 12CQ chip is a world-first qubit processor technology the Company is developing that would allow for mobile quantum computing powered devices. The Company for the first time has detected quantum information in the 12CQ qubit material on-chip and at room temperature using mobile phone compatible technology (ASX ann. 1 Feb 2022).

Archer and teams from the world-class institute EPFL (École Polytechnique Fédérale de Lausanne), located in Switzerland, have now used a single-chip integrated electron spin resonance (“ESR”) detector based on a high electron mobility transistor (“HEMT”) technology to detect and characterize the as-prepared 12CQ qubit material in a controlled atmosphere at room temperature.

The signal characteristics obtained agreed with the well-studied, repeatable, and scientifically published results obtained from room temperature measurements performed on macroscopic (‘bulk’) quantities of the qubit material using continuous wave ESR instruments.

The unoptimised ESR chip devices were of sufficient sensitivity to detect the electron spin in a few picolitres (picolitre is a trillionth of a litre) of qubit material at room temperature. The quantum information in the qubit material is in the form of an electron’s ‘spin’ states. The quantum states were found to be sufficiently well preserved when operating in an on-chip environment.

The single-chip resonator was developed at EPFL, and manufactured by semiconductor company OMMIC using existing foundry processes and facilities, near Paris, France. HEMT devices are widely used in integrated circuits, for example in mobile phones, and are well-known in the semiconductor industry due to their low power consumption (the HEMT based ESR detector chip device referred to in this Announcement consumed approximately 90 µW of power at room temperature operation).

The HEMT technology was initially utilized for the ESR chip in part to confirm the advantages of low power consumption offered by a HEMT for the qubit measurements, and the chip having simplified integrated electronics to a single transistor. The coherent control of quantum information in qubit materials is the fundamental requirement for quantum logic operations that are the basis of any quantum computing qubit processor hardware. For potential development and use of Archer’s qubit materials in practical quantum processor chip devices, it is significant to demonstrate the room temperature detection of quantum information using mobile-compatible device technology.

By demonstrating the detection of electron spin quantum states using a single chip ESR detector based on HEMT, the technology paves the way for the implementation of the complex qubit control characteristics required in quantum circuits.

Source: https://archerx.com.au/src/uploads/2022/04/20220426_Quarterly-Activities-Report-ASX-Release.pdf

I know the 5th DiVincenzo Criteria states, "A qubit-specific measurement capability." When Archer states that they can detect and characterize the quantum information and the electronic spin specifically, would that satisfy the DiVincenzo Criteria? In other words, is detect/characterize synonymous with measure in this context?

$\endgroup$

1 Answer 1

1
+50
$\begingroup$

There is linked paper to this article "Room temperature manipulation of long lifetime spins in metallic-like carbon nanospheres".

I believe it clearly confirms control and measurement possibility:

"Following the observation of spin polarization by electron spin resonance, we control the quantum state of the electron spin by applying short bursts of an oscillating magnetic field and observe coherent oscillations of the spin state.

These results demonstrate the feasibility of operating electron spins in conducting carbon nanospheres as quantum bits at room temperature. [...]

Electron spin states are an attractive realization of a quantum bit (qubit) as they can undergo a transition between the spin-up and spin-down quantum states (ref. 1)."

And then ref. 1 is exactly: DiVincenzo, D. P. Quantum computation. Science 270, 255 (1995).

From David P. DiVincenzo paper "The Physical Implementation of Quantum Computation" stating:

"Five (plus two) requirements for the implementation of quantum computation

  1. A scalable physical system with well characterized qubits

[...] A qubit (or, more precisely, the embodiment of a qubit) is [25] simply a quantum two-level system like the two spin states of a spin 1/2 particle,

  1. A qubit-specific measurement capability

Finally, the result of a computation must be read out, and this requires the ability to measure specific qubits. In an ideal measurement, if a qubit’s density matrix is

$ρ = p\vert 0 \rangle \langle 0 \vert + (1 − p)\vert 1 \rangle \langle 1 \vert + α\vert 0 \rangle \langle 1 \vert + α^*\vert 1 \rangle \langle 0 \vert$,

the measurement should give outcome “0” with probability $p$ and “1” with probability $1 − p$ independent of $α$ and of any other parameters of the system, including the state of nearby qubits, and without changing the state of the rest of the quantum computer.

If the measurement is “nondemolition”, that is, if in addition to reporting outcome “0” the measurement leaves the qubit in state $\vert 0 \rangle \langle 0 \vert$, then it can also be used for the state preparation of requirement 2; but requirement 2 can be fulfilled in other ways."

Regarding measurements Archer announced second stage development dedicated to commercialization.

It looks like they successfully performed first measurement on a single qubit component.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.