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My quantum computing study notes (may add to this later)

Torchickens
Apr 16th, 2022 (edited)
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  1. #Thx Wikipedia
  2.  
  3. A qubit might use the spin of an electron (i.e. up, down, etc???) or polarization of a photon
  4. (verticial polarisation, horizontal polarisation, etc???)
  5. ---
  6.  
  7. Spin (intrinsic) (s as opposed to S)
  8.  
  9. ---
  10.  
  11. Spin quantum - 'intrinsic' to a subatomic particle including fermions (quarks, leptons, antiquarks, antileptons);
  12. "Matter particles" "Antimatter particles"
  13. - and
  14.  
  15. Bosons (gauge bosons, Higgs boson)
  16. "Force particles"; mediating interactions among fermions
  17.  
  18.  
  19. -;Compare with
  20. Spin angular
  21.  
  22.  
  23. Examples:-
  24.  
  25. Fermions:-
  26. known spins =1/2
  27. participate in strong interaction (strong nuclear force)
  28. obey Fermi–Dirac statistics
  29. have half-integer spins
  30.  
  31. -Inline citation is
  32.  
  33. Braibant, Sylvie; Giacomelli, Giorgio; Spurio, Maurizio (2012). Particles and Fundamental Interactions: An introduction to particle physics (2nd ed.). Springer. ISBN 978-94-007-2463-1.
  34.  
  35.  
  36. Known are
  37.  
  38. --Quarks and antiquarks ; has "color charge",
  39. (E.g. up/u, down/d, charm/c, strange/s, top/t, bottom/b),
  40.  
  41. --Leptions and anti-leptons ; has no "color charge":
  42. known spins =1/2
  43. participate in electroweak interactions (electroweak force)
  44.  
  45. --
  46. ; Because that other article mentioned you might use an electron's spin (which is a lepton), I decided to read "Electron magnetic moment" too re: how it may be used in quantum computing
  47.  
  48. "In atomic physics, the electron magnetic moment, or more specifically the electron magnetic dipole moment, is the magnetic moment of an electron caused by its intrinsic properties of spin and electric charge. The value of the electron magnetic moment is approximately −9.284764×10−24 J/T. The electron magnetic moment has been measured to an accuracy of 7.6 parts in 10^13.[1]"
  49.  
  50. # From https://en.wikipedia.org/w/index.php?title=Electron_magnetic_moment&oldid=1073727617
  51.  
  52. - Magnetic moment is "the magnetic strength and orientation of a magnet or other object that produces a magnetic field. "
  53. https://en.wikipedia.org/wiki/Magnetic_moment
  54.  
  55. Study later to see if there's anything more clear
  56.  
  57. https://www.google.com/search?q=how+is+the+electron+spin+used+in+quantum+computing
  58. https://scholar.google.com/scholar?hl=en&as_sdt=0%2C5&q=how+is+the+electron+spin+used+in+quantum+computing&btnG=
  59.  
  60. --
  61.  
  62. --
  63. ; As for polarisation of a photon and how it may be used in quantum computing
  64.  
  65. https://en.wikipedia.org/wiki/Photon_polarization
  66.  
  67. https://www.google.com/search?q=how+is+photon+polarization+used+in+quantum+computing
  68. https://scholar.google.com/scholar?hl=en&as_sdt=0%2C5&q=how+is+photon+polarization+used+in+quantum+computing&btnG=
  69.  
  70. "The polarization of light can be used to encode quantum information. Light is made up of indivisible particles called photons. Quantum researchers can create photons one-at-a-time and encode quantum bits of information into their polarization.
  71.  
  72. Light polarization | Institute for Quantum Computing
  73. https://uwaterloo.ca/institute-for-quantum-computing/outreach/quantum-toolbox/light-polarization#:~:text=Quantum%20connection,of%20information%20into%20their%20polarization.
  74.  
  75. - Looks like a really useful website; read through more of it too?
  76. --
  77.  
  78.  
  79. (Examples of leptons and antileptons, electron/e, electron neutrino v[e], muon μ, muon neutrino v[μ], tau [τ], tau neutrino v[τ])
  80. −
  81. -
  82.  
  83. Bosons;
  84.  
  85. obey Bose–Einstein statistics (above source)
  86. known spins =1,2 (gauge) and 0 (scalar)
  87. have integer spins
  88.  
  89.  
  90. ;Gauge bosons
  91. spin can be 1. 2 is proposed but is about the graviton which is only a hypothesis (not adequately proven)[‡; see next [‡]]
  92. force carriers ("a force carrier, also known as messenger particle or intermediate particle, is a type of particle that gives rise to forces between other particles.")
  93. "[‡] The known force carrier bosons all have spin = 1 and are therefore vector bosons. The hypothetical graviton has spin = 2 and is a tensor boson; it is unknown whether it is a gauge boson as well."
  94.  
  95.  
  96. - We know of
  97.  
  98. Photon (γ; electromagnetic interaction)
  99.  
  100. W and Z (W+, W−, Z; weak interaction)
  101.  
  102.  
  103. Gluons (specifically the eight colors but these can have nine possible color and anticolor combinations https://wikimedia.org/api/rest_v1/media/math/render/svg/fe95f01c29982ebdb1073e864d66409d5fac1e27 - g; strong interactions)
  104. - furthermore the combinations include
  105. red-antired (r r-), red-antigreen (r g-), red-antiblue (r b-)
  106. green-antired (g r-), green-antigreen (g g-), green-antiblue (g b-)
  107. blue-antired (b r-), blue-antigreen (b g-), blue-antiblue (b b-)
  108. (effective rather than actual)
  109. "To correctly understand how they are combined, it is necessary to consider the mathematics of color charge in more detail."
  110. - Gluons bind quarks together, forming hadrons such as protons and neutrons.
  111.  
  112. The graviton is proposed however it is hypothetical (applies to the field of quantum gravity which the academic 'consensus' is it hasn't been solved)
  113. (G)
  114.  
  115. ;Scalar boson
  116. spin can be 0
  117.  
  118. Includes the Higgs boson (H[0])
  119. spin 0
  120. the parity transformation (sign of one spatial coordinate) is: even+postive
  121. no colour charge
  122. couples with (interacts with) mass
  123. very unstable decaying into other particles 'almost immediately'
  124.  
  125. "The Higgs field is a scalar field, with two neutral and two electrically charged components that form a complex doublet of the weak isospin SU(2) symmetry. Its "Mexican hat-shaped" potential has a nonzero value everywhere (including otherwise empty space), which breaks the weak isospin symmetry of the electroweak interaction, and via the Higgs mechanism gives some particles mass."
  126.  
  127. -Scalar field refers to assigning a scalar value to a space (but not necessarily a physical one)
  128. ---
  129.  
  130. Polarisation
  131.  
  132. ---
  133.  
  134. Polarization (waves)
  135. - When you pull on a guitar string, depending on how you plucked it, the vibrations might be vertical, horizontal, at an angle(..).
  136.  
  137. "According to quantum mechanics, electromagnetic waves can also be viewed as streams of particles called photons. When viewed in this way, the polarization of an electromagnetic wave is determined by a quantum mechanical property of photons called their spin.[7][8] A photon has one of two possible spins: it can either spin in a right hand sense or a left hand sense about its direction of travel. Circularly polarized electromagnetic waves are composed of photons with only one type of spin, either right- or left-hand. Linearly polarized waves consist of photons that are in a superposition of right and left circularly polarized states, with equal amplitude and phases synchronized to give oscillation in a plane.[8]"
  138.  
  139. Inline citations are here https://en.wikipedia.org/w/index.php?title=Polarization_(waves)&oldid=1071683152
  140.  
  141. ---
  142. Spin angular momentum (S as opposed to s)
  143. ---
  144.  
  145. Quantised and follows the formula below
  146.  
  147. "where h (Planck constant) and (h=(h/2pi)) is the reduced Planck constant.
  148.  
  149. Orbital angular momentum can only take on integer values of s; i.e., even-numbered values of n."
  150.  
  151. https://wikimedia.org/api/rest_v1/media/math/render/svg/c85d7682e45045d420df3a4c6d4b7105501d151c
  152.  
  153.  
  154.  
  155. Read later;
  156. https://en.wikipedia.org/wiki/Quantum_entanglement
  157. https://en.wikipedia.org/wiki/Concurrence_(quantum_computing)
  158. https://en.wikipedia.org/wiki/Stern%E2%80%93Gerlach_experiment
  159. https://en.wikipedia.org/wiki/Quantum_superposition
  160. https://en.wikipedia.org/wiki/Category:Quantum_information_science
  161. https://en.wikipedia.org/wiki/Category:Theoretical_computer_science
  162. > "It [also] includes theoretical issues in computational models as well as more experimental topics in quantum computing."
  163. >> Scrape through to see which ones apply
  164.  
  165. - Example of an actual chip
  166.  
  167. https://en.wikipedia.org/wiki/Horse_Ridge_(chip)
  168.  
  169. The Wikipedia article is currently quite short, so try to find more specific information on how it works both in accordance to the physical world and architecture - specifically too; assembly/machine code is deemed a "Low-level programming language" - because I don't know much about quantum mechanics, is this relevant to Horse Ridge too? Say there is a quantum assembly language - I'd be really interested in trying to learn it by experimentation especially since it says "New features include the ability to manipulate and read qubit states (and drive up to 16 spin qubits with a direct digital synthesis (DDS) architecture) and control the potential of multiple gates needed to correlate multiple qubits (features 22 high-speed digital-to-analog converters (DACs))." (it's fun to learn through reverse engineering, hex editing and using BGB debugger to learn GBZ80 taught me much more than actual docs/theory - it was only because of reverse engineering I could start to understand the Pan Docs etc. better, so why don't more people do it?), but acquiring a quantum chip currently seems far too hard, (or is it easier now?).
  170.  
  171. -- It's based on CMOS technology
  172. -- How is it used? Because a CMOS process is used for constructing integrated circuit (IC) chips, including microprocessors, microcontrollers, memory chips according to https://en.wikipedia.org/w/index.php?title=CMOS&action=history
  173. -- Specifically, what type of chip? The article says control chip; and due to the nature of quantum mechanics it's cryogenic, operating from close to 0 Kelvin and up, but is there more elaboration?
  174.  
  175. -- News
  176.  
  177. https://www.techradar.com/uk/news/intel-is-making-some-mysterious-moves-in-quantum-computing
  178. (12 April 2022)
  179.  
  180. https://www.intel.com/content/www/us/en/newsroom/news/2nd-gen-horse-ridge-cryogenic-quantum-control-chip.html
  181. (3 December 2020)
  182.  
  183. "Scalability is the measure of a system's ability to increase or decrease in performance and cost in response to changes in application and system processing demands." https://www.gartner.com/en/information-technology/glossary/scalability#:~:text=Scalability%20is%20the%20measure%20of,application%20and%20system%20processing%20demands.
  184. --On this note, there is considered a competition for this to happen, and "quantum supremacy" and the 'race for it' is a buzz-word - a company that has been overtaken financially may want this too (as to come on top again). The issue too is a company like Intel may want their technology (physical, engineering, construction) and documentation (re: subjects like assembly, code and debugging), also (among scientists not just computer engineers, programmers) the science involved, confidential at first. These are also very powerful companies; it would be hard to get anything at all, and if we did it might cost lots?
  185.  
  186. However, the techradar article suggests practically (in terms of transitioning from theory into practice) this is finally going to happen - and eventually within the hands of the general public hopefully. An issue is accessibility as well. How might an average person go to a lab to experiment near 0 Kelvin and learn how to construct/engineer the technology. Is it simply far too expensive? (and companies like Intel for this reason have a capital until these are publicly viable?) Can you cool a system down to near 0 Kelvin (Absolute Zero) without an official contract with a lab/organisation/etc?
  187.  
  188.  
  189. https://arxiv.org/pdf/1803.01774.pdf
  190. -Read (spin lifetime and charge noise; implications on how Intel used this to implement quantum computing at higher temperatures because " leading solid-state approaches function only at temperatures below 100 millikelvin, where cooling power is extremely limited, and this severely affects the prospects of practical quantum computation. "
  191. https://www.nature.com/articles/s41586-020-2170-7
  192. https://data.4tu.nl/articles/dataset/Data_for_Universal_quantum_logic_in_hot_silicon_qubits/12682778/1 - data underlying the above study on nature
  193.  
  194. @May 23 2022 - To do: Watch Sabine Hossenfelder's videos
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