FLUCTUATION AND NOISE EXPLOITATION LABORATORY

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Myth-busting in Physics and Information Technology

Picture of MythBusters on
                              Discovery Channel

What we show in this page
below is similar in nature to the Discovery Channel's MythBusters (see on the left) who bust or verify everyday myths, except that we do this within the professional fields of science and technology. As a consequence, while our story can sometimes be as funny as their show; the stakes and the matters are much more serious with potential impacts on the direction of science/technology and its funding. The sad part of the story is that there is a flood of new myths in science, in the popular science media and even in some of the leading scientific journals. The myths usually come with a great hype that can potentially discredit reasonable scientific claims, if the present trend continues.
 


Below,
a few of the important myths that we had busted are shown, in (roughly) inverse-chronological-order. We focus on myths where stochastics has a role (explicit or implicit).


1. Unconditionally secure communications (key exchange) provided by the laws of physics  (2005-present)

Myth: It had generally been assumed that only quantum physics was able to provide unconditional security of the key exchange. Securing a classical wire without a previously exchanged secret key seemed to be impossible because the current and voltage are measurable without disturbing the system (at least in the ideal situation).

Status of myth: Busted.

Reason: It has been shown that classical thermodynamics (statistical physics) and Kirchhoff's loop law can also provide an unconditionally secure key exchange. In the ideal situation of the Kirchhoff-law-Johnson-noise (KLJN) scheme, the Second Law of Thermodynamics guarantees perfect ecurity. Consequently, it is as impossible to crack the KLJN scheme as to build a perpetual motion machine (of the second kind). In the non-ideal case, similarly to ideal quantum key exchange, there is an information leak about the key toward the eavesdropper. However, this information leak can be suppressed below any required level, which means unconditional security. The price is invested resources such as cost of wires and/or time invested into the exchange of secure key bits. Out of the Second Law, the security of the non-ideal case utilizes the finite information of a band-limited stochastic signal of finite duration (time-error uncertainty principle of statistics).

General security proof of KLJN utilizing the continuity of functions in stable classical physical systems: L.B. Kish, C.G. Granqvist, "On the security of the Kirchhoff-law-Johnson-noise (KLJN) communicator", Quantum Information Processing (2013), in press.

Most extensive/deep recent review:  L.B. Kish, D. Abbott, C.G. Granqvist, "Critical Analysis of the Bennett–Riedel Attack on Secure Cryptographic Key Distributions via the Kirchhoff-Law–Johnson-Noise Scheme", PLOS ONE  8 (2013) e81810.

Brief introductory text, less advanced aspects: D. Abbott, G. Schmera, "Secure communications using the KLJN scheme", Scholarpedia 8 (2013) 31157.


2. Energy dissipation of control; Maxwell demon and Szilard engine (2011-present)

Myth-1: It had generally been assumed that, in the Szilard engine, controlling the motion/position of the piston during restoring the initial state requires negligible amount of energy dissipation compared to the work the Szilard engine can produce.

Status of myth-1: Busted.

Reasons: It has been shown that, in the limit of 50% error probability (that is at 0% efficiency), the minimum energy dissipated at any single-bit operation is greater than kT ln(2), which is equal to the net work the Szilard engine can produce when the efficiency 100%. Thus even a single bit operation with reasonable (non-zero) error probability would dissipate more energy than work the engine can produce at any efficiency. It is shown that the control operation of restoring the piston's position at the end of the cycle requires at lest 5 single-bit operations, that is, at least 5 kT ln(2) energy dissipation even at zero efficiency of these operations. This is 5 times more than the work the Szilard engine can produce at 100% efficiency, therefore this effect alone can save the Second Law of Thermodynamics. See much more in:

L.B. Kish, C.G. Granqvist, "Energy Requirement of Control: Comments on the Maxwell Demon and the Szilard Engine"
EPL 98
(2012) 68001. (Note: a former version utilizing equivalence theory was published in the conference proceedings book "All the colors of noise. Essays in Honor of Lino Reggiani" in 2010).

=============

Myth-2: It has often been assumed that, in a Maxwell demon and Szilard engine, the energy dissipation in the memory is the component that is unavoidable and dominant at ideal conditions.

Status of myth-2: Busted.

Reason: By introducing an improved Maxwell demon and Szilard engine
that are utilizing Johnson noise, measurement, logic and control to quantitatively analyze the energy requirement of  all  components during the  full  cycle of operation, it is proven that the analog part of the demon/engine, which is essential in the physical realization of any measurement/decision process, dissipates exponentially more energy than the binary part of the system (including the memory), when the energy output of these engines is increased. See much more in:

L.B. Kish, C.G. Granqvist, "
Electrical Maxwell Demon and Szilard Engine Utilizing Johnson Noise, Measurement, Logic and Control",
PLoS ONE  7 (2012) e46800.


3. Twisted radio waves to enhance wireless capacity (2012-2013)

Myth: Orbital wave modes (twisted wave modes) offer independent information channels on top of the two, classically used, polarization modes. If this myth were true, twisted wave modes could offer virtually infinite information channel capacity in a classical single wireless frequency band.  See this BBC news item and the linked paper.

Status of myth: Busted.

Reason: The assumption that the orbital wave modes in the far-field of radio waves represent information channels that are
independent from both basic polarization waves violates the Second Law of Thermodynamics, that is, allows the construction of a perpetual motion machine (of the second kind). If it were true, using a resistor and a twisted-wave-antenna, one could pump thermal energy into an absorbing wall at the same temperature as the resistor; while the plane-wave radiation from the wall would not be able to re-feed this energy into the resistor. Such a violation of the detailed balance of energy allows the construction of a perpetual motion machine (of the second kind). In conclusion, any twisted-wave antenna must be sensitive to at least one of the polarization components of plane waves otherwise the Second Law of Thermodynamics is violated. That means, twisted waves do not represent new, independent information channels.

See: L.B. Kish, R.D. Nevels, "Twisted Radio Waves and Twisted Thermodynamics",
PLoS ONE 8(2): e56086 (open access).

- BBC news item mentioning this at the end.




4. Physical systems for high-efficiency computation with small hardware and time complexity (2009-present)

Myth-1: It has been generally supposed that noise in a logic system is the source of errors (even though neural signals in the brain are noise) and to avoid these problems a large energy dissipation is required in a computer.

Status of myth-1: Busted. Noise-based logic utilizes the noise in the system as information carrier.

Myth-2: It has been generally supposed that only quantum systems can represent and manipulate 2^N bits by O(N) (or polynomial) hardware and time complexity.

Status of myth-2:
Busted. Noise-based logic offers the same exponential performance enhancement potential by utilizing classical statistical physics.
 
Myth-3: It has been generally supposed that the logic signal in the brain is statistical: it is either the mean frequency of neural pulses or the statistical correlations between these frequencies at different points of the brain. 

Status of myth-3: Busted. Noise-based brain-logic utilizes coincidence events of single neural spikes instead of statistics and achieves exponential speedup.

  See more at the Noise-based logic page.




More (older) myth-busting stories:


5. Energy dissipation in general-purpose classical and quantum computers (2004-05)

6. Moore's laws of miniaturization (2003-05)

7. Lognormal size distribution of nanoparticles by advanced gas evaporation (1998)

8. Stochastic resonance (1994-96; 2001)

9. High-temperature superconductors (1990-94)

10. Self-organized criticality (1990)

11.
Universal conductance fluctuations (1990)

12. Quantum 1/f noise model (1986-87)
         

 
 








 

 

 

 

 

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