Carmen G. Almudéver
Delft University of Technology
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Featured researches published by Carmen G. Almudéver.
computing frontiers | 2016
X. Fu; L. Riesebos; Lingling Lao; Carmen G. Almudéver; Fabio Sebastiano; Edoardo Charbon; Koen Bertels
In this paper, we present a high level view of the heterogeneous quantum computer architecture as any future quantum computer will consist of both a classical and quantum computing part. The classical part is needed for error correction as well as for the execution of algorithms that contain both classical and quantum logic. We present a complete system stack describing the different layers when building a quantum computer. We also present the control logic and corresponding data path that needs to be implemented when executing quantum instructions and conclude by discussing design choices in the quantum plane.
design, automation, and test in europe | 2017
Carmen G. Almudéver; Lingling Lao; X. Fu; Nader Khammassi; Imran Ashraf; Dan Iorga; S. Varsamopoulos; C. Eichler; A. Wallraff; L. Geck; A. Kruth; Joachim Knoch; H. Bluhm; Koen Bertels
Quantum computers may revolutionize the field of computation by solving some complex problems that are intractable even for the most powerful current supercomputers. This paper first introduces the basic concepts of quantum computing and describes what the required layers are for building a quantum system. Thereafter, it discusses the different engineering challenges when building a quantum computer ranging from the core qubit technology, the control electronics, to the microarchitecture for the execution of quantum circuits and efficient quantum error correction. We conclude by discussing some compiler and programming issues relative to quantum algorithms.
design, automation, and test in europe | 2017
Nader Khammassi; Imran Ashraf; X. Fu; Carmen G. Almudéver; Koen Bertels
Quantum computing is rapidly evolving especially after the discovery of several efficient quantum algorithms solving intractable classical problems such as Shors factoring algorithm. However the realization of a large-scale physical quantum computer is very challenging and the number of qubits that are currently under development is still very low, namely less than 15. In the absence of large size platforms, quantum computer simulation is critical for developing and testing quantum algorithms and investigating the different challenges facing the design of quantum computer hardware. What makes quantum computer simulation on classical computers particularly challenging are the memory and computational resource requirements. In this paper, we introduce a universal quantum computer simulator, called QX, that takes as input a specially designed quantum assembly language, called QASM, and provides, through agressive optimisations, high simulation speeds and large number of qubits. QX allows the simulation of up to 34 fully entangled qubits on a single node using less than 270 GB of memory. Our experiments using different quantum algorithms show that QX achieves significant simulation speedup over similar state-of-the-art simulation environment.
computing frontiers | 2016
Harald Homulle; Stefan Visser; Bishnu Patra; Giorgio Ferrari; Enrico Prati; Carmen G. Almudéver; Koen Bertels; Fabio Sebastiano; Edoardo Charbon
We propose a classical infrastructure for a quantum computer implemented in CMOS. The peculiarity of the approach is to operate the classical CMOS circuits and systems at deep-cryogenic temperatures (cryoCMOS), so as to ensure physical proximity to the quantum bits, thus reducing thermal gradients and increasing compactness. CryoCMOS technology leverages the CMOS fabrication infrastructure and exploits the continuous effort of miniaturization that has sustained Moores Law for over 50 years. Such approach is believed to enable the growth of the number of qubits operating in a fault-tolerant fashion, paving the way to scalable quantum computing machines.
arXiv: Quantum Physics | 2018
Lingling Lao; B. van Wee; Imran Ashraf; J. van Someren; Nader Khammassi; Koen Bertels; Carmen G. Almudéver
Quantum error correction (QEC) and fault-tolerant (FT) mechanisms are essential for reliable quantum computing. However, QEC considerably increases the computation size up to four orders of magnitude. Moreover, FT implementation has specific requirements on qubit layouts, causing both resource and time overhead. Reducing spatial-temporal costs becomes critical since it is beneficial to decrease the failure rate of quantum computation. To this purpose, scalable qubit plane architectures and efficient mapping passes including placement and routing of qubits as well as scheduling of operations are needed. This paper proposes a full mapping process to execute lattice surgery-based quantum circuits on two surface code architectures, namely a checkerboard and a tile-based one. We show that the checkerboard architecture is 2x qubit-efficient but the tile-based one requires lower communication overhead in terms of both operation overhead (up to 86%) and latency overhead (up to 79%).
international symposium on microarchitecture | 2017
X. Fu; M. A. Rol; C. C. Bultink; J. van Someren; Nader Khammassi; Imran Ashraf; R. F. L. Vermeulen; J. C. de Sterke; W. J. Vlothuizen; R. N. Schouten; Carmen G. Almudéver; L. DiCarlo; Koen Bertels
Quantum computers promise to solve certain problems that are intractable for classical computers, such as factoring large numbers and simulating quantum systems. To date, research in quantum computer engineering has focused primarily at opposite ends of the required system stack: devising high-level programming languages and compilers to describe and optimize quantum algorithms, and building reliable low-level quantum hardware. Relatively little attention has been given to using the compiler output to fully control the operations on experimental quantum processors. Bridging this gap, we propose and build a prototype of a flexible control microarchitecture supporting quantum-classical mixed code for a superconducting quantum processor. The microarchitecture is based on three core elements: (i) a codeword-based event control scheme, (ii) queue-based precise event timing control, and (iii) a flexible multilevel instruction decoding mechanism for control. We design a set of quantum microinstructions that allows flexible control of quantum operations with precise timing. We demonstrate the microarchitecture and microinstruction set by performing a standard gate-characterization experiment on a transmon qubit. CCS CONCEPTS. • General and reference → General conference proceedings; • Computer systems organization → Quantum computing; • Hardware → Quantum technologies;
international conference on design and technology of integrated systems in nanoscale era | 2018
Carmen G. Almudéver; Nader Khammassi; Louis Hutin; M. Vinet; Masoud Babaie; Fabio Sebastiano; Edoardo Charbon; Koen Bertels
A quantum machine may solve some complex problems that are intractable for even the most powerful classical computers. By exploiting quantum superposition and entanglement phenomena, quantum algorithms can achieve from polynomial to exponential speed up when compared to their best classical counterparts. A quantum computer will be a part of a heterogeneous, multi-core computer in which a classical processor will interact with several accelerators such as FPGAs, GPUs and also a quantum co-processor. Figure 1 shows the different layers of the quantum computer system stack [1]. Building such a quantum system requires contributions from different fields such as physics, electronics, computer science and computer engineering for addressing the following challenges: i) build scalable quantum chips integrating qubits with long coherence times and high-fidelity operations, ii) develop classical control electronics at possibly cryogenic temperatures and iii) create the microarchitecture as well as the software for quantum computation.
design automation conference | 2017
L. Riesebos; X. Fu; S. Varsamopoulos; Carmen G. Almudéver; Koen Bertels
The Pauli frame mechanism allows Pauli gates to be tracked in classical electronics and can relax the timing constraints for error syndrome measurement and error decoding. When building a quantum computer, such a mechanism may be beneficial, and the goal of this paper is not only to study the working principles of a Pauli frame but also to quantify its potential effect on the logical error rate. To this purpose, we implemented and simulated the Pauli frame module which, in principle, can be directly mapped into a hardware implementation. Simulation of a surface code 17 logical qubit has shown that a Pauli frame can reduce the error rate of a logical qubit up to 70% compared to the same logical qubit without Pauli frame when the decoding time equals the error correction time, and maximum parallelism can be obtained.
international conference on design and technology of integrated systems in nanoscale era | 2018
Carmen G. Almudéver; Nader Khammassi; Louis Hutin; M. Vinet; Masoud Babaie; Fabio Sebastiano; Edoardo Charbon; Koen Bertels
arXiv: Quantum Physics | 2018
Christophe Vuillot; Lingling Lao; Ben Criger; Carmen G. Almudéver; Koen Bertels; Barbara M. Terhal