Start a hangout

## Profile

Ravi Kunjwal

Worked at Perimeter Institute for Theoretical Physics

Attends The Institute of Mathematical Sciences ("Matscience"), Chennai

276 followers|137,697 views

AboutPostsPhotosVideos

## Stream

### Ravi Kunjwal

Shared publicly -A statistician says a major scientific publisher is hindering his research.

1

Add a comment...

### Ravi Kunjwal

Shared publicly -A webcomic of romance, sarcasm, math, and language. We've almost eradicated polio. For World Polio Day, I drew a comic about the eradication efforts. You can see it on Bill Gates's blog. My new book of complex diagrams and simple words comes out Nov 24th. DNA. |< · < Prev · Random; Next >; >| ...

1

Add a comment...

### Ravi Kunjwal

Shared publicly -This is happening in a few hours.

Dear All,

We are happy to announce a Q+ Hangout for the month of November, on the recent "loophole-free Bell test"! Bas Hensen will tell us about this experiment. As usual, if you are watching with a group and want to reserve a seat in the hangout then leave a comment. We also encourage individuals interested in active participation---which typically involves asking questions after the talk---to join the hangout. Otherwise you can watch on the livestream. Details follow.

Speaker: Bas Hensen, QuTech, Kavli Institute of Nanoscience Delft, Delft University of Technology.

Title: Experimental loophole-free violation of a Bell inequality using entangled electron spins separated by 1.3 km.

Abstract: In his seminal work[1], John Bell proved that no theory of nature that obeys locality, realism and free will can reproduce all the predictions of quantum theory. In the past decades, numerous ingenious Bell inequality tests have been reported. However, because of experimental limitations, all experiments to date required additional assumptions to obtain a contradiction with local realism, resulting in loopholes. I will present the main result [2] of my PhD, a Bell experiment that is free of any such additional assumption and thus directly tests the principles underlying Bell's inequality. We employ an event-ready scheme that enables the generation of high-fidelity entanglement between distant electronic spins [3]. Efficient spin readout [4] avoids the fair sampling assumption (detection loophole), while the use of fast random basis selection and readout combined with a spatial separation of 1.3 km ensure the required locality conditions. This result rules out large classes of local realist theories, and paves the way for implementing device-independent quantum-secure communication and randomness certification. In combination with the control of nuclear spins around the NV centre [5,6], it establishes the NV centre as a prime candidate for the node of a future quantum network [7]. I will discuss the set of optical and microwave control techniques used, discuss the limitations of the NV centre, and possible improvements.

[1] Bell, J. S. On the Einstein-Podolsky-Rosen paradox. Physics 1, 195 (1964).

[2] B. Hensen, H. Bernien, A.E. Dréau, A. Reiserer, N. Kalb, M.S. Blok, J. Ruitenberg, R.F.L. Vermeulen, R.N. Schouten, C. Abellán, W. Amaya, V. Pruner, M. W. Mitchell, M. Markham, D.J. Twitchen, D. Elkouss, S. Wehner, T.H. Taminiau, R. Hanson. Experimental loophole-free violation of a Bell inequality using entangled electron spins separated by 1.3 km. arXiv:1508.05949 (2015).

[3] H. Bernien, B. Hensen, W. Pfaff, G. Koolstra, M. S. Blok, L. Robledo, T. H. Taminiau, M. Markham, D. J. Twitchen, L. Childress, R. Hanson. Heralded entanglement between solid-state qubits separated by three meters. Nature 497, 86 (2013)

[4] L. Robledo, L. Childress, H. Bernien, B. Hensen, P.F. A. Alkemade, R. Hanson. High-fidelity projective read-out of a solid-state spin quantum register. Nature 477, 547 (2011).

[5] W. Pfaff, B. Hensen, H. Bernien, S. B. van Dam, M. S. Blok, T. H. Taminiau, M. J. Tiggelman, R. N., Schouten, M. Markham, D. J. Twitchen, R. Hanson. Unconditional quantum teleportation between distant solid-state qubits. Science 345, 532 (2014).

[6] J. Cramer, N. Kalb, M. A. Rol, B. Hensen, M. S. Blok, M. Markham, D. J. Twitchen, R. Hanson & T. H. Taminiau. Quantum error correction by stabilizer measurements and feedback. Submitted (2015).

[7] H. J. Kimble, The quantum internet. Nature 453, 1023 (2008).

We are happy to announce a Q+ Hangout for the month of November, on the recent "loophole-free Bell test"! Bas Hensen will tell us about this experiment. As usual, if you are watching with a group and want to reserve a seat in the hangout then leave a comment. We also encourage individuals interested in active participation---which typically involves asking questions after the talk---to join the hangout. Otherwise you can watch on the livestream. Details follow.

Speaker: Bas Hensen, QuTech, Kavli Institute of Nanoscience Delft, Delft University of Technology.

Title: Experimental loophole-free violation of a Bell inequality using entangled electron spins separated by 1.3 km.

Abstract: In his seminal work[1], John Bell proved that no theory of nature that obeys locality, realism and free will can reproduce all the predictions of quantum theory. In the past decades, numerous ingenious Bell inequality tests have been reported. However, because of experimental limitations, all experiments to date required additional assumptions to obtain a contradiction with local realism, resulting in loopholes. I will present the main result [2] of my PhD, a Bell experiment that is free of any such additional assumption and thus directly tests the principles underlying Bell's inequality. We employ an event-ready scheme that enables the generation of high-fidelity entanglement between distant electronic spins [3]. Efficient spin readout [4] avoids the fair sampling assumption (detection loophole), while the use of fast random basis selection and readout combined with a spatial separation of 1.3 km ensure the required locality conditions. This result rules out large classes of local realist theories, and paves the way for implementing device-independent quantum-secure communication and randomness certification. In combination with the control of nuclear spins around the NV centre [5,6], it establishes the NV centre as a prime candidate for the node of a future quantum network [7]. I will discuss the set of optical and microwave control techniques used, discuss the limitations of the NV centre, and possible improvements.

[1] Bell, J. S. On the Einstein-Podolsky-Rosen paradox. Physics 1, 195 (1964).

[2] B. Hensen, H. Bernien, A.E. Dréau, A. Reiserer, N. Kalb, M.S. Blok, J. Ruitenberg, R.F.L. Vermeulen, R.N. Schouten, C. Abellán, W. Amaya, V. Pruner, M. W. Mitchell, M. Markham, D.J. Twitchen, D. Elkouss, S. Wehner, T.H. Taminiau, R. Hanson. Experimental loophole-free violation of a Bell inequality using entangled electron spins separated by 1.3 km. arXiv:1508.05949 (2015).

[3] H. Bernien, B. Hensen, W. Pfaff, G. Koolstra, M. S. Blok, L. Robledo, T. H. Taminiau, M. Markham, D. J. Twitchen, L. Childress, R. Hanson. Heralded entanglement between solid-state qubits separated by three meters. Nature 497, 86 (2013)

[4] L. Robledo, L. Childress, H. Bernien, B. Hensen, P.F. A. Alkemade, R. Hanson. High-fidelity projective read-out of a solid-state spin quantum register. Nature 477, 547 (2011).

[5] W. Pfaff, B. Hensen, H. Bernien, S. B. van Dam, M. S. Blok, T. H. Taminiau, M. J. Tiggelman, R. N., Schouten, M. Markham, D. J. Twitchen, R. Hanson. Unconditional quantum teleportation between distant solid-state qubits. Science 345, 532 (2014).

[6] J. Cramer, N. Kalb, M. A. Rol, B. Hensen, M. S. Blok, M. Markham, D. J. Twitchen, R. Hanson & T. H. Taminiau. Quantum error correction by stabilizer measurements and feedback. Submitted (2015).

[7] H. J. Kimble, The quantum internet. Nature 453, 1023 (2008).

This Hangout On Air is hosted by Q+. The live video broadcast will begin soon.

Q&A

Preview

Live

Q+ Hangout: Bas Hensen

Thu, November 12, 9:00 AM

Hangouts On Air - Broadcast for free

1

Add a comment...

### Ravi Kunjwal

Shared publicly -Hey all, I’m back! I’ve been stuck in a black hole for the past couple years. Nobody ever said that doing a PhD in quantum gravity would be easy. Actually, my advisor John Preskill explicitly warne...

1

3

Taufik Yusof

+

1

2

1

2

1

cc: +David Roberts

Add a comment...

### Ravi Kunjwal

Shared publicly -Erica Klarreich tackles the (nontrivial) task of explaining the Kadison-Singer problem and its solution.

1

Add a comment...

### Ravi Kunjwal

Shared publicly -"The wide-ranging talks and participants forced me to take a broad perspective on randomness and question some of the most deeply ingrained “certainties” that underlie my research (such as a firm — though baseless — belief that the Copenhagen interpretation is the only reasonable interpretation of quantum mechanics worthy of a practicing scientist)."

1

Add a comment...

Work

Occupation

Graduate student (Theoretical Physics) at IMSc, Chennai.

Employment

- Perimeter Institute for Theoretical PhysicsVisiting Graduate Fellow
- The Institute of Mathematical SciencesGraduate student ("Senior Research Fellow")

Basic Information

Gender

Male

Looking for

Friends, Networking

Story

Tagline

i came, i saw, and i still wonder

Education

- The Institute of Mathematical Sciences ("Matscience"), ChennaiTheoretical Physics, 2010 - present
- St. Stephen's College, DelhiPhysics, 2007 - 2010
- St. Thomas' College, Dehradun2002 - 2007
- St. John Bosco College, Lucknow1993 - 2002

Links

YouTube

Other profiles