Long Hoang Nguyen

ICARUS-Q: A scalable RFSoC-based control system for superconducting quantum computers

  1. Kun Hee Park,
  2. Yung Szen Yap,
  3. Yuanzheng Paul Tan,
  4. Christoph Hufnagel,
  5. Long Hoang Nguyen,
  6. Karn Hwa Lau,
  7. Stavros Efthymiou,
  8. Stefano Carrazza,
  9. Rangga P. Budoyo,
  10. and Rainer Dumke
We present a control and measurement setup for superconducting qubits based on Xilinx 16-channel radio frequency system on chip (RFSoC) device. The proposed setup consists of four parts:
multiple RFSoC FPGA boards, a setup to synchronise every DAC and ADC channel across multiple boards, a low-noise DC current supply for qubit biasing and cloud access for remotely performing experiments. We also design the setup to be free of physical mixers. The FPGA boards directly generate microwave pulses using sixteen DAC channels up to the third Nyquist zone which are directly sampled by its eight ADC channels between the fifth and the ninth zones.
arxiv pdf

Ghost Factors in Gauss Sum Factorization with Transmon Qubits

  1. Lin Htoo Zaw,
  2. Yuanzheng Paul Tan,
  3. Long Hoang Nguyen,
  4. Rangga P. Budoyo,
  5. Kun Hee Park,
  6. Zhi Yang Koh,
  7. Alessandro Landra,
  8. Christoph Hufnagel,
  9. Yung Szen Yap,
  10. Teck Seng Koh,
  11. and Rainer Dumke
A challenge in the Gauss sums factorization scheme is the presence of ghost factors – non-factors that behave similarly to actual factors of an integer – which might lead
to the misidentification of non-factors as factors or vice versa, especially in the presence of noise. We investigate Type II ghost factors, which are the class of ghost factors that cannot be suppressed with techniques previously laid out in the literature. The presence of Type II ghost factors and the coherence time of the qubit set an upper limit for the total experiment time, and hence the largest factorizable number with this scheme. Discernability is a figure of merit introduced to characterize this behavior. We introduce preprocessing as a strategy to increase the discernability of a system, and demonstrate the technique with a transmon qubit. This can bring the total experiment time of the system closer to its decoherence limit, and increase the largest factorizable number.
arxiv pdf

An experimental platform for hybridization of atomic and superconducting quantum systems

  1. Alessandro Landra,
  2. Christoph Hufnagel,
  3. Lim Chin Chean,
  4. Thomas Weigner,
  5. Yung Szen Yap,
  6. Long Hoang Nguyen,
  7. and Rainer Dumke
Hybrid quantum systems have the potential of mitigating current challenges in developing a scalable quantum computer. Of particular interest is the hybridization between atomic and
superconducting qubits. We demonstrate a novel experimental setup for transferring and trapping ultracold atoms inside a millikelvin cryogenic environment, where interactions between atomic and superconducting qubits can be established, paving the way for hybrid quantum systems. 87Rb atoms are prepared in a conventional magneto-optical trap and transported via a magnetic conveyor belt into a UHV compatible dilution refrigerator with optical access. We store 5×108 atoms with a lifetime of 794 seconds in the vicinity of the millikelvin stage.
arxiv pdf