[HN Gopher] Single atom defect in 2D material can hold quantum i...
___________________________________________________________________
Single atom defect in 2D material can hold quantum information at
room temp
Author : westurner
Score : 74 points
Date : 2024-05-23 23:53 UTC (1 days ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| smegsicle wrote:
| > single atomic defect can hold onto quantum information for
| microseconds under ambient conditions
|
| how long could... a hundred atomic defects?
| krastanov wrote:
| There are a couple of ways to answer your question:
|
| - If we are talking about storing one qubit per defect:
| reproducibly/reliably/scalably creating such defects in large
| numbers is impossible for now, so the answer is either "they
| simply can not be built" or "just as long as a single defect if
| we imagine we could build them"
|
| - If we are talking about storing one qubit in a 100 defects:
| same issues as above hold, but if we imagine that we can build
| a 100 defects... and if we imagine we have control over such
| ensemble of defects... and if we imagine we can perform logic
| gates between neighboring defects, then we can use error
| correcting codes, so a hundred atomic defects can store the
| equivalent of one logical qubit for (exponentially) longer than
| a single defect. But all the things I am imagining here are
| impossible for the moment (but people are working on it).
| krastanov wrote:
| To provide some context:
|
| - Usually the problem with room temperature is that the various
| thermal mechanical excitation and thermal radiation surrounding
| the qubit lead to interaction with the qubit and the information
| stored in it "leaks"; that is the main reason a lot of quantum
| hardware needs cryogenics.
|
| - There are already a couple of similar types of "defects" that
| are known as a promising way to retain superposition states at
| room temperature. They work because the defect happens to be
| mechanically and/or optically isolated from the rest of the
| environment due to some idiosyncrasies in its physical
| composition.
|
| - You might have heard of "trapped ion" or "trapped neutral atom"
| quantum hardware. In those the qubits are atoms (or the electrons
| of atoms) and they are trapped (with optical or RF tweezers) so
| they are kept accessible. The type of "defects" discussed here
| are "simply" atoms trapped in a crystal lattice instead of
| trapped in optical tweezers -- there are various tradeoffs for
| that choice.
|
| - While discoveries like this are extremely exciting, there is a
| completely separate set of issues about scalability, reliability,
| longevity, controlability, and reproducible fabrication of
| devices like this. That is true for any quantum hardware and
| while there are great improvements over the last 15 years and
| while there is truly exponential progress over that time, we are
| still below the threshold of this technology being engineeringly
| and economically useful.
|
| Lastly, the usual reminder: there are a few problems in
| computing, communication, and sensing, where quantum devices can
| do things that are impossible classically, but these are very
| restricted and niche problems. For most things a classical device
| is not only practically better today, but also is in-principle
| better even if quantum computers become trivial to build.
| epsilonic wrote:
| What class of problems benefit significantly from being solved
| by quantum devices?
| smarm52 wrote:
| Some helpful resources:
|
| https://quantumcomputing.stackexchange.com/questions/1584/is.
| ..
|
| https://www.researchgate.net/post/Are-there-any-examples-
| of-...
| xeonmc wrote:
| how stable are nuclei excitation states with respect to
| environmental perturbation?
| chasil wrote:
| >Usually the problem with room temperature is that the various
| thermal mechanical excitation and thermal radiation surrounding
| the qubit lead to interaction with the qubit and the
| information stored in it "leaks"; that is the main reason a lot
| of quantum hardware needs cryogenics.
|
| This issue, as I understand it, is quantum decoherence, when
| quantum properties are lost as an object transitions into the
| behavior of classical physics.
|
| The article describes a period of a millisecond before quantum
| decoherence occurs. This is (relatively) a long time, and
| perhaps could be exploited in part to build a quantum computer.
|
| https://en.m.wikipedia.org/wiki/Quantum_decoherence
| gliptic wrote:
| Decoherence is what GP means with information leakage. The
| quantum state of the object becomes correlated with the
| environment.
|
| The article is saying this can be avoided in their system for
| a _microsecond_, still long enough to be potentially useful.
| westurner wrote:
| From "Computer-generated holography with ordinary display"
| (2024) https://opg.optica.org/viewmedia.cfm?r=1&rwjcode=ol&
| uri=ol-4... :
|
| > The hologram cascade is synthesized by solving _an
| inverse problem with respect to the propagation of
| incoherent light._
|
| From "Learning quantum Hamiltonians at any temperature in
| polynomial time" (2024) https://arxiv.org/abs/2310.02243 ..
| https://news.ycombinator.com/item?id=40396171 :
|
| >> _The relaxation technique is well known in the field of
| approximation algorithms, but it had never been tried in
| quantum learning._
|
| Relaxation (iterative method)
| https://en.wikipedia.org/wiki/Relaxation_(iterative_method)
|
| Pertubation theory > History > Beginnings in the study of
| planetary motion ... QFT > History: https://en.wikipedia.or
| g/wiki/Perturbation_theory#Beginnings...
|
| QFT > History:
| https://en.wikipedia.org/wiki/Quantum_field_theory#History
| :
|
| > _Quantum field theory emerged from the work of
| generations of theoretical physicists spanning much of the
| 20th century. Its development began in the 1920s with the
| description of interactions between light and electrons,
| culminating in the first quantum field theory--quantum
| electrodynamics._ A major theoretical obstacle soon
| followed with the appearance and persistence of various
| infinities in perturbative calculations, a problem only
| resolved in the 1950s with the invention of the
| renormalization procedure. _A second major barrier came
| with QFT 's apparent inability to describe the weak and
| strong interactions, to the point where some theorists
| called for the abandonment of the field theoretic approach.
| The development of gauge theory and the completion of the
| Standard Model in the 1970s led to a renaissance of quantum
| field theory._
|
| But the Standard Model Lagrangian doesn't describe n-body
| gravity, n-body quantum gravity, photons in Bose-Einstein
| Condensates; liquid light in superfluids and
| superconductors, black hole thermodynamics and external or
| internal topology, unreversibility or not, or even fluids
| with vortices or curl that certainly affect particles
| interacting in multiple fields.
|
| TIL again about Relaxation theory for solving _quantum_
| Hamiltonians.
|
| OTOH other things on this topic
|
| - "Coherent interaction of a-few-electron quantum dot with
| a terahertz optical resonator" (2023)
| https://arxiv.org/abs/2204.10522 :
|
| > _By illuminating the system with THz radiation_ [a wave
| function (Hamiltonian) is coherently transmitted over a
| small chip-scale distance]
|
| - "Room Temperature Optically Detected Magnetic Resonance
| of Single Spins in GaN" (2024)
| https://www.nature.com/articles/s41563-024-01803-5 ... "GAN
| semiconductor defects could boost quantum technology"
| https://news.ycombinator.com/item?id=39365467
|
| - "Reversible non-volatile electronic switching in a near-
| room-temperature van der Waals ferromagnet" (2024)
| https://www.nature.com/articles/s41467-024-46862-z ...
| "Nonvolatile quantum memory: Discovery points path to
| flash-like qubit storage" (2024)
| https://news.ycombinator.com/item?id=39956368 :
|
| >> _" That's the key finding," she said of the material's
| switchable vacancy order. "The idea of using vacancy order
| to control topology is the important thing. That just
| hasn't really been explored. People have generally only
| been looking at materials from a fully stoichiometric
| perspective, meaning everything's occupied with a fixed set
| of symmetries that lead to one kind of electronic topology.
| Changes in vacancy order change the lattice symmetry. This
| work shows how that can change the electronic topology. And
| it seems likely that vacancy order could be used to induce
| topological changes in other materials as well."_
|
| - "Catalog of topological phonon materials" (2024)
| https://www.science.org/doi/10.1126/science.adf8458 ...
| "Topological Phonons Discovered and Catalogued in Crystal
| Lattices" (2024-05)
| https://news.ycombinator.com/item?id=40410475
|
| - "Observation of current whirlpools in graphene at room
| temperature" (2024)
| https://www.science.org/doi/10.1126/science.adj2167 ..
| "Electron Vortices in Graphene Detected"
| https://news.ycombinator.com/item?id=40360691 :
|
| > re: the fractional quantum hall effect, and decoherence:
| _How are spin currents and vorticity in electron vortices
| related?_
| Sniffnoy wrote:
| Non-AMP version: https://phys.org/news/2024-05-scientists-atom-
| defect-2d-mate...
| fuzzfactor wrote:
| The first time I handled boron nitride I knew it was different
| than most other materials.
| vlovich123 wrote:
| Is this for implementing something akin to SRAM or registers for
| a future hypothetical QC or could this improve classical
| storage/memory somehow?
| lightweightbaby wrote:
| These kind of atom-like systems can be used as registers for a
| quantum computer. They allow you to store a qubit and apply
| gates to that qubit. It doesn't make practical sense to use it
| to improve classical storage, although it actually can pack
| more information than a classical bit using "superdense coding"
| [0]
|
| [0] https://en.m.wikipedia.org/wiki/Superdense_coding
___________________________________________________________________
(page generated 2024-05-25 23:00 UTC)