In the News

September 17, 2020

Extended flag gadgets for low-overhead circuit verification

A new work has been posted on the arXiv entitled 'Extended Flag Gadgets for Low-Overhead Circuit Verification.' In this work we propose an extension to the flag qubit framework which can be applied in a more general setting. Our gadgets can detect faults on generic unitaries, and are low overhead [...]

Ca ion and molecualr ion

August 20, 2020

Manipulating molecular ion qubits

Our new preprint on coupling molecular and atomic ion qubits can be found at arXiv:2008.09201 .This work is in collaboration with the Eric Hudson and Wes Campbell groups at UCLA and Michael Heaven at Emory University.   In this article we discuss a novel laser-free method of using an atomic ion for [...]

QCCD Figure

April 10, 2020

Architecting noisy intermediate-scale trapped ion quantum computers

New paper published in the International Symposium on Computer Architecture (ISCA2020)!


March 13, 2020

Critical faults of leakage errors on the surface code

Leakage is a particularly damaging error that occurs when a qubit leaves the defined computational subspace.


March 12, 2020

Photon-mediated charge-exchange reactions between 39K atoms and 40Ca+ ions in a hybrid trap

Our detailed study of photon-mediated charge exchange between cold Potassium atoms and calcium ions is published in the journal Physical Chemistry Chemical Physics.

Brown Lab

January 13, 2020

Brown Lab at QIP2020

Brown lab at QIP2020 in Shenzhen. Posters about quantum error correction by Natalie, Shilin, Dripto, and Muyuan. Talks about quantum error correction by Mike and Ken.


November 13, 2019

Brown lab at SESAPS 2019

Brown lab attended the Southeastern Section of the American Physical Society (SESAPS) in Wilmington.

Spectator qubit poster at APQC

October 18, 2019

Brown Lab at APQC Workshop

Swarnadeep Majumder attended the Assessing Performance of Quantum Computers (APQC) workshop in Estes Park, CO and presented a poster on Real Tiime Calibration Using Spectator Qubits.


October 17, 2019

Generating Fault-Tolerant Cluster States from Crystal Structures

Quantum information is delicate. To preserve it, we must constantly interact with our system in order to remove errors.


August 5, 2019

A hybrid ion-atom trap with integrated high resolution mass spectrometer

Cold molecular ions are good candidates for precision measurements such as the time variation of proton to electron mass ratio.

August 4, 2019

Brown Lab at QEC19

Brown lab attended the 5th International Conference on Quantum Error Correction in London.

July 16, 2019

Watching the Errors with Spectator Qubits

Quantum computers promise to be a technological revolution, but they will only be possible if the error rate of quantum bits (qubits) is kept under a manageable level. Many techniques have been developed to control, mitigate, and correct quantum errors, and the most appropriate choice depends [...]

June 4, 2019

Brown Lab at TQC + NISQ

Ken Brown and Swarnadeep Majumder attend TQC 2019 conference + NISQ workshop.  Ken presents an invited talk on Error Reduction, Fault Tolerance, and Scalability at TQC.  Swarnadeep presents a poster on real-time calibration with spectator qubits at the NISQ workshop. 

May 14, 2019

Leakage Mitigation Using Quantum Error Correction in a Mixed Ion Scheme

  Mixed species surface code layout. Hyperfine (171Yb+) ions are defined as ancilla qubits (white) and Zeeman (174Yb+) ions are defined as data qubits (black). The green (blue) diamond represents an X (Z) stabilizer measurement.   Leakage errors are exceptionally damaging errors that occur when a [...]

March 12, 2019

Handling Leakage with Subsystem Codes

The distance-3 and distance-5 rotated subsystem surface codes.  Although the weight-6 rectangular stabilizers are larger than the weight-4 stabilizer of the surface code, they can be measured in pairs of triangular gauge operators.  This locality limits correlated errors due to leakage, resulting [...]