• John
  • Felde
  • University of Maryland
  • USA

Latest Posts

  • James
  • Doherty
  • Open University
  • United Kingdom

Latest Posts

  • Andrea
  • Signori
  • Nikhef
  • Netherlands

Latest Posts

  • CERN
  • Geneva
  • Switzerland

Latest Posts

  • Aidan
  • Randle-Conde
  • Université Libre de Bruxelles
  • Belgium

Latest Posts

  • TRIUMF
  • Vancouver, BC
  • Canada

Latest Posts

  • Laura
  • Gladstone
  • MIT
  • USA

Latest Posts

  • Steven
  • Goldfarb
  • University of Michigan

Latest Posts

  • Fermilab
  • Batavia, IL
  • USA

Latest Posts

  • Seth
  • Zenz
  • Imperial College London
  • UK

Latest Posts

  • Nhan
  • Tran
  • Fermilab
  • USA

Latest Posts

  • Alex
  • Millar
  • University of Melbourne
  • Australia

Latest Posts

  • Ken
  • Bloom
  • USLHC
  • USA

Latest Posts

|

Read Bio

Solving the Measurement Problem (Guest Post)

Wednesday, October 5th, 2016

The following is a guest posting from Ken Krechmer of the College of Engineering at Applied Science at the University of Colorado, at Boulder. 

Ken Krechmer

Ken Krechmer

The dichotomy between quantum measurement theory and classical measurement results has been termed: the measurement disturbance, measurement collapse and the measurement problem.   Experimentally it is observed that the measurement of the position of one particle changes the momentum of the same particle instantaneously.  This is described as the measurement disturbance.  Quantum measurement theory calculates the probability of a measurement result but does not calculate an actual measurement result.  What occurs that causes the quantum measurement probability to collapse into a classical measurement result?  Different approaches have been proposed to resolve one or both of these issues including hidden variables, non-local variables and decoherence, but none of these approaches appear to fully resolve both these aspects of the measurement problem.

Further complicating this measurement problem: 1. The quantum effect called entanglement is another measurement disturbance where the measurement of one particle instantaneously impacts a similar measurement of another, far remote, particle.  2. The quantum effect called uncertainty which defines the minimum variation between two measurement results and changes depending on the order of the two measurements.

Relational measurements and uncertainty,” also available at Measurement, resolves both aspects of the measurement problem by expanding the definition of a classical measurement to include sampling and calibration to a reference. Experimentally, it is well known that a measurement must be sampled and calibrated to a reference to establish a measurement result. This paper proves that the measurement collapse is due to the effect of sampling and calibration which is equal to the universal quantum measurement uncertainty.  The universal quantum measurement uncertainty has been verified in independent quantum experiments. Next, one quantum measurement is shown to instantaneously disturb another because one sampling and calibration process is applied to both measurement results.

 The paper resolves the dichotomy between quantum theory and classical measurement results, derives the quantum uncertainty relations using classical physics, unifies the measurement process across all scales and formally models calibration and sampling.


ABOUT KEN KRECHMER

Ken Krechmer, University of Colorado (CU) Scholar in Residence, has taught a graduate level engineering course on standards and standardization at CU.  He authored prize winning papers on standards and standardization in 1995, 2000, 2006 and 2012. Krechmer co-founded the journal Communications Standards Review.  He was active in standardization committees in the ITU, ETSI, TIA, IEEE, and many consortia for over 20 years.  Krechmer is a Senior Member of the IEEE and a Member of Society of Engineering Standards.

Share

A Summer of Quantum Strings

Tuesday, December 2nd, 2014

Salvish Goomanee, an undergraduate theoretical physics student, penned the following post about his summer research at King’s College London.

Salvish Goomanee

Salvish Goomanee

This past summer, I had a brief glimpse into what it’s like to carry out theoretical research. As an undergraduate, this was an exciting foray into what I hope will be my future! The work was done under the supervision of a research associate of the theoretical physics department at King’s College London, who was kind enough to accept my proposal. We decided to look at some perturbative amplitudes of the open bosonic string, which gave me the chance to peek into the obscure world of quantum strings. (Bear with me – I’ll explain what all that means soon enough!) I was presented with several very interesting challenges during the course of the research; it was not always easy but it was great to have the chance to experience with the various mathematical methods that permeate the fundamental formalism of string theory.

After our first meeting, which lasted for about three hours, I found myself with notes and calculations and a long list of references which seemed to be the basics for understanding perturbative string theory. I obviously was not aware of what was going on but this was the beginning of the three long months of studying the new and rigorous concepts of quantum field theory and some slightly more advance mathematics as well. The goal of the research was to understand the path integral formulation and apply it to the framework of the bosonic string.

In short, bosonic string theory is a type of string theory that deals only with bosons which are integer spin particles. To understand that a bit better, let’s leave string theory for a brief moment and consider the construction plan for a new building. Architects and engineers will work out a much smaller model first (which I am sure we have all seen!), where it would be much easier to have control upon and therefore have a better understanding how things will look like at much larger scales. Physicists will do the same thing as calculations for the bosonic string can be performed at energy scales that are relatively low. Therefore amplitudes calculated via small perturbations can be pictured as new particles. Quantum field theory is extensively employed during such processes. (Quantum field theory is basically the merging of special relativity and the laws of quantum mechanics. String theory is actually a quantum field theory that incorporates gravity which the Standard Model of particle physics does not!)

So, here I was, an undergraduate who just finished the second year exams, facing all this new stuff that I had to study and make sense of. It was challenging and somehow a bit frightening. You reach a point where you ask yourself why you should continue doing these things when it was not making much sense, but giving up was not an option! The good thing was that I would be able to finally apply the few little things I learnt from relativity (field equations, cosmological solutions and tensors, etc). Being familiar with the theory of geometrization of space-time proved to be a very good support as the notation used in perturbative string theory was then much easier to understand. It’s actually extensively employed everywhere in theoretical physics. Finally we were then able to see (and I was able to contemplate!) the various predictions, good and bad, of string theory.

This experience was something which I definitely enjoyed. I guess what made it better was the great summer we had here in London. Obviously during the hottest days we could not (and did not want to) really work inside, so we discussed our ideas our outside. One day we even spent more than four hours talking; this was one of the rare moments where an undergraduate gets to know in a bit more detail the kind of research their supervisors and lectures carry out and the level at which it is done. In the end, I was able to produce a report in which I discussed the stuff we went through. We are now looking at some other applications of the quantum strings in greater detail. All in all, it was a wonderful summer, and I’m thrilled that we’re still collaborating!

Share

Brookhaven, CERN, Fermilab and TRIUMF Join Quantum Diaries

Monday, January 10th, 2011

Living in an era when the latest discoveries in physics regularly make headlines, it can be easy to miss the individual contributions from the scientists and institutions around the globe making these advances possible. Highlighting these contributions, along with the quirky world from physicists working behind the scenes, has been the focus of Quantum Diaries since it launched in 2005.

Quantum Diaries is sure to continue in that role, but today relaunches with four physics laboratories in its ranks: Brookhaven, CERN, Fermilab and TRIUMF. Each of the laboratories will be posting regular updates to Quantum Diaries.

All of the labs have already gotten started. In its first post, Brookhaven Laboratory provides a thorough description of its current physics work. CERN, aware of the challenges of fitting complex scientific explanations into 140-character tweets, hopes this new forum will give the laboratory a place to expand on the news of the day coming from the LHC and other experiments. Fermilab details a number of expectations for 2011, including updates on the Higgs search, more data from its neutrino experiments, the launch and construction of several experiments, and a decision that the Tevatron will shut down in September 2011. Finally, Canadian physics laboratory TRIUMF explores the difficulty of summing the full range of its work, from manufacturing isotopes to treating eye cancer, in a single catchy name.

As these laboratories continue to contribute to the site, Quantum Diaries welcomes commenting, feedback and constructive discussions on each post. Check back for frequent updates from our new laboratory members, as well as continued updates from our regular Quantum Diaries bloggers.

Brookhaven

thumbnail

Brookhaven National Laboratory is a multipurpose research institution funded by the U.S. Department of Energy. Located on Long Island, NY, Brookhaven operates large-scale facilities for studies in physics, chemistry, biology, medicine, applied science, and advanced technology. The Laboratory's almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.

CERN

thumbnail

CERN is one of the world's largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world's largest and most complex scientific instruments are used to study the basic constituents of matter: fundamental particles.

Fermilab

thumbnail

What is the nature of the universe? What are matter and energy, space and time? At the U.S. Department of Energy's Fermi National Accelerator Laboratory, thousands of scientists from universities and laboratories across the United States and around the world collaborate on experiments to discover what the universe is made of and how it works.

TRIUMF

thumbnail

Located in Vancouver, British Columbia, TRIUMF is Canada's national laboratory for particle and nuclear physics. The laboratory is owned and operated as a joint venture by a consortium of 16 Canadian universities and celebrated its fortieth anniversary in 2009. TRIUMF brings together dedicated physicists and interdisciplinary talent, sophisticated technical resources, and commercial partners in a way that has established the laboratory as a global success.

Share