A few days ago my colleague at University of Latvia, +Andris Ambainis, has shown me a recent preprint by +Ross Anderson and +Robert Brady. The title and the content of their paper are so provocative (e.g., "

As a condensed matter physicist, I'd like to state a few things that I hope will quickly clarify this confusion. Below are you will find a list of statements regarding arXiv:1301.7351 by Anderson and Brady (A&B) and arXiv:1301.7540 by Brady. You don't have to trust me - run the list by any tenured physicist at your university/department.

*full range of quantum phenomena from completely classical motion*" and "*quantum cryptography is not probably secure*") that it has understandably attracted some attention of the cryptography community and led to sensational news reports attributed to "Cambridge experts".As a condensed matter physicist, I'd like to state a few things that I hope will quickly clarify this confusion. Below are you will find a list of statements regarding arXiv:1301.7351 by Anderson and Brady (A&B) and arXiv:1301.7540 by Brady. You don't have to trust me - run the list by any tenured physicist at your university/department.

- There is no explicit model for entanglement (or any other kind of many-particle correlation) in Brady's "sonon" model of an electron or in the A&B preprint.
- As a corollary, the model is irreconcilable with each of the myriad of experimental facts underlying our trust in the conventional quantum many-body theory (ie., Shcrodinger equation in Fock space). Explicitly:
- Spectrum of any atom beyond hydrogen.
- Superconductivity (from which Josephson-effect-based QIP is derived).
- Anomalous value of electron's gyromagnetic ratio (which by itself long ago has fundamentally invalidated any single-particle approximation for the physical electron, including Dirac equation which Brady connects his model to).
- Exchange interaction and ferromagnetism.
- The Standard Model of particle physics.

- Another corollary: in contrast to standard theory, A&B provide no alternative method to compute the outcome of any of Bell-inequality testing experiment. (The latter belong the same myriad of experimental keyholes that quantum theory has successfully passed through).
- Brady's use of the historical name "fine structure constant" for his estimate of the squared dimensionless Coulomb charge of the "sonon" ($\alpha < 1/49$) is misleading. There is no spin-orbit interaction in his model and hence no prediction for fine structure of atomic spectra.

One can go on and pick apart individual superficial analogies put forward by A&B that a non-specialist may mistake for valid criticism of contemporary quantum theory, but I hope that I have made it clear enough that scientific implications of the controversy stirred by A&B, if any, do not belong to the domain of physical sciences.