Speaker: Dr. Sudipto Chakraborty, IBM T.J. Watson Research Center
Date: Tuesday, September 26
Time: 1:00pm - 2:00pm
Location: EIT-3142
Abstract:
Practical challenges for cryogenic CMOS designs for next generation quantum computing will be described. Starting from the system level, the design considerations for a non-multiplexed, semi-autonomous, transmon qubit state controller (QSC) implemented in 14-nm CMOS FinFET technology are detailed. The QSC includes an augmented general-purpose digital processor that supports waveform generation and phase rotation operations combined with a low-power current-mode single-sideband upconversion I/Q mixer-based RF arbitrary waveform generator (AWG). Implemented in 14-nm CMOS FinFET technology, the QSC generates control signals in its target 4.5GHz to 5.5 GHz frequency range, achieving an SFDR > 50dB for a signal bandwidth of 500MHz. With the controller operating in the 4-K stage of a cryostat and connected to a transmon qubit in the cryostat’s millikelvin stage, measured transmon T1 and T2 coherence times were 75.7μs and 73μs, respectively, in each case comparable to results achieved using conventional room temperature controls. In further tests with transmons, a qubit-limited error rate of 7.76x10-4 per Clifford gate is achieved, again comparable to results achieved using room temperature controls. The QSC’s maximum RF output power is -18 dBm, and power dissipation per qubit under active control is 23mW.
Biography:
Sudipto Chakraborty received the B. Tech from Indian Institute of Technology, Kharagpur in 1998, and the Ph.D. in E.E. from the Georgia Institute of Technology in 2002. He worked as a researcher in the Georgia Electronic Design Center (GEDC) until 2004. From 2004 to 2016, he was a senior Member of the Technical Staff at Texas Instruments, where he contributed to lowpower integrated circuit design for more than 10 product families in the areas of automotive, wireless, medical, and microcontrollers. Since 2017, Sudipto has been working at the IBM T.J. Watson Research Center, where he leads the low-power circuit design for next generation quantum computing applications using nano-CMOS technologies. He has authored or coauthored more than 75 papers, two books and holds 86 U.S. patents. Dr. Chakraborty has served on the technical program committees of various conferences including the IEEE-CICC, RFIC, and IMS conferences, and was elected as an IBM master inventor in 2022 for his contributions.
