Akshay N Gaikwad - Academia.edu (original) (raw)

Papers by Akshay N Gaikwad

Physical Review A

We experimentally implement the Sz.-Nagy dilation algorithm to simulate open quantum dynamics on ... more We experimentally implement the Sz.-Nagy dilation algorithm to simulate open quantum dynamics on an nuclear magnetic resonance (NMR) quantum processor. The Sz.-Nagy algorithm enables the simulation of the dynamics of arbitrary-dimensional open quantum systems, using only a single ancilla qubit. We experimentally simulate the action of two non-unitary processes, namely, a phase damping channel acting independently on two qubits and a magnetic field gradient pulse (MFGP) acting on an ensemble of two coupled nuclear spin-1/2 particles. To evaluate the quality of the experimentally simulated quantum process, we perform convex optimization-based full quantum process tomography to reconstruct the quantum process from the experimental data and compare it with the target quantum process to be simulated.

Quantum Information Processing

We employ the compressed sensing (CS) algorithm and a heavily reduced data set to experimentally ... more We employ the compressed sensing (CS) algorithm and a heavily reduced data set to experimentally perform true quantum process tomography (QPT) on an NMR quantum processor. We obtain the estimate of the process matrix χ corresponding to various two-and three-qubit quantum gates with a high fidelity. The CS algorithm is implemented using two different operator bases, namely, the standard Pauli basis and the Pauli-error basis. We experimentally demonstrate that the performance of the CS algorithm is significantly better in the Pauli-error basis, where the constructed χ matrix is maximally sparse. We compare the standard least square (LS) optimization QPT method with the CS-QPT method and observe that, provided an appropriate basis is chosen, the CS-QPT method performs significantly better as compared to the LS-QPT method. In all the cases considered, we obtained experimental fidelities greater than 0.9 from a reduced data set, which was approximately five to six times smaller in size than a full data set. We also experimentally characterized the reduced dynamics of a two-qubit subsystem embedded in a three-qubit system, and used the CS-QPT method to characterize processes corresponding to the evolution of two-qubit states under various J-coupling interactions.

Scientific Reports

The experimental implementation of selective quantum process tomography (SQPT) involves computing... more The experimental implementation of selective quantum process tomography (SQPT) involves computing individual elements of the process matrix with the help of a special set of states called quantum 2-design states. However, the number of experimental settings required to prepare input states from quantum 2-design states to selectively and precisely compute a desired element of the process matrix is still high, and hence constructing the corresponding unitary operations in the lab is a daunting task. In order to reduce the experimental complexity, we mathematically reformulated the standard SQPT problem, which we term the modified SQPT (MSQPT) method. We designed the generalized quantum circuit to prepare the required set of input states and formulated an efficient measurement strategy aimed at minimizing the experimental cost of SQPT. We experimentally demonstrated the MSQPT protocol on the IBM QX2 cloud quantum processor and selectively characterized various two- and three-qubit quan...

Quantum Information Processing, 2021

We use a constrained convex optimization (CCO) method to experimentally characterize arbitrary qu... more We use a constrained convex optimization (CCO) method to experimentally characterize arbitrary quantum states and unknown quantum processes on a two-qubit NMR quantum information processor. Standard protocols for quantum state and quantum process tomography are based on linear inversion, which often result in an unphysical density matrix and hence an invalid process matrix. The CCO method on the other hand, produces physically valid density matrices and process matrices, with significantly improved fidelity as compared to the standard methods. The constrained optimization problem is solved with the help of a semi-definite programming (SDP) protocol. We use the CCO method to estimate the Kraus operators and characterize gates in the presence of errors due to decoherence. We then assume Markovian system dynamics and use a Lindblad master equation in conjunction with the CCO method to completely characterize the noise processes present in the NMR qubits.

International Journal of Advance Research and Innovative Ideas in Education, 2018

The objective ‘modern plant cutting machine’ is to come up with a mover that is portable, durable... more The objective ‘modern plant cutting machine’ is to come up with a mover that is portable, durable, easy to operate and maintain .It comprises of a system of speed multiplication pulleys which drive the cutting blades and lift mechanism meant to alter the height of the cut. This is achieved by means of a system of chain with minimum slip effect; collapsible blades to reduce the common problem of wear. The prime mover is used as tractor having high efficiency with small amount of human effort. Thus, the machine is considered highly efficient and is readily adaptable to different cutting conditions. Now, in India the plant cutting is done by manually i.e. by the application of human effort. So on behalf of these types of plant cutting we have to made ‘modern plant cutting machine’ which is efficient, less noisy , portable and less time consuming .the basic idea is that we have made plant cutter with prime mover as tractor that runs from a 20 HP. Road accidents are now globally recogniz...

International Journal of Quantum Information, 2020

We experimentally performed complete and optimized quantum process tomography of quantum gates im... more We experimentally performed complete and optimized quantum process tomography of quantum gates implemented on superconducting qubit-based IBM QX2 quantum processor via two constrained convex optimization (CCO) techniques: least squares optimization and compressed sensing optimization. We studied the performance of these methods by comparing the experimental complexity involved and the experimental fidelities obtained. We experimentally characterized several two-qubit quantum gates: identity gate, a controlled-NOT gate, and a SWAP gate. The general quantum circuit is efficient in the sense that the data needed to perform CCO-based process tomography can be directly acquired by measuring only a single qubit. The quantum circuit can be extended to higher dimensions and is also valid for other experimental platforms.

Journal of The Institution of Engineers (India): Series E, 2020

Boron-based nanostructures are considered as alternative hydrogen storage material due to its lar... more Boron-based nanostructures are considered as alternative hydrogen storage material due to its large surface area, lightweight and chemical stability. In this work, the hydrogen storage capacity and structural evolution of titanium (Ti) atoms-decorated B 40 fullerene are investigated using first-principles calculations. Our result shows that Ti prefers to absorb on the outside surface of the hexagonal and heptagonal cavities of B 40 ring. The average binding energy (E binding) for 6 Ti atoms-decorated B 40 structure is calculated as 5.71 eV. The interatomic distance between two neighbor Ti atoms (5.13-5.54 Å) is larger than that of Ti 2 dimer (* 2.0 Å) to prevent the aggregation of Ti atoms as well as Ti n cluster formation. The average adsorption energies (E adsorption) for (Ti-nH 2) 6 B 40 (n = 2-6) structures, within a range of 0.29-0.33 eV, prove that the structures are between chemisorbed and physisorbed states (0.2-0.6 eV). We have achieved a maximum gravimetric density (H 2 wt%) of 9.3 wt% exceeding the 5.5 wt% goal set by the Department of Energy, USA, by the year 2020. In addition, ab initio molecular dynamics calculations have confirmed that the (Ti-6H 2) 6 B 40 structure is stable for the hydrogen adsorption under near-ambient temperature.

International Journal for Research in Applied Science and Engineering Technology, 2020

Blockchain is a distributed, decentralized, public ledger for securely exchanging digital currenc... more Blockchain is a distributed, decentralized, public ledger for securely exchanging digital currency and transaction information. Blockchain was invented in 2008 by satoshi Nakamoto as public ledger for cryptocurrency bitcoin. Blockchain allows the participants to verify the transactions independently. This paper explains the concept of blockchain, characteristics, how blockchain works, and its security mechanisms. It attempts to highlights role of Blockchain in various fields. Key aspects: Improved accuracy by removing human involvement in verification. Cost reductions by eliminating third-party verification Decentralization makes it harder to tamper with. Transactions are secure, private and efficient. Transparent technology. I.

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 5, 2017

A pyrene-based colorimetric chemosensor 1-(pyren-1-yl)-N,N-bis-(pyridine-2-ylmethyl)methanamine (... more A pyrene-based colorimetric chemosensor 1-(pyren-1-yl)-N,N-bis-(pyridine-2-ylmethyl)methanamine (1) was synthesised for selective detection of Cu (II) and Fe (III) over the other metal cations Ni(2+), Mg(2+), Cd(2+), Hg(2+), Na(+), K(+), Ca(2+), Co(2+), Cr(3+), Pb(2+) and Zn(2+). The significant changes in UV-vis absorption band of receptor 1 and the emergence of 660nm band in presence of Cu(2+) ion indicates the selective binding of Cu(2+) ion as compared to other metal cations which could easily be identified from the naked eye strong colour change. Job plots suggest a 1:1 and 2:1 stoichiometric binding of Cu(2+) and Fe(3+), respectively, which was evidenced by ESI-MS analysis. Chemosensor 1 explores a cost-effective and selective colorimetric sensor for naked eye detection of trace amount of Cu(2+) and Fe(3+) ions in presence of other metal cations.

Archiv der Pharmazie, 2009

During recent decades, a considerable attention has been paid to structurally diverse purine deri... more During recent decades, a considerable attention has been paid to structurally diverse purine derivatives possessing various types of biological activity. 1-3 Among them, compounds exhibiting anti viral, 4-8 antitumor, 9-12 antimycobacterial 13-16 and other types of biological activity were found. Recently, we have studied the in vitro antimycobacterial activity of novel purin-6-yl derivatives of dipeptides and amino acids. 17,18 Within this family, purin-6-yl and 2-aminopurin-6-yl conjugates with glycyl-(S)-glutamic acid (compounds 1a,b) show the highest inhibitory activity against both laboratory strains of Myco bacterium tuberculosis and clinical isolates of multidrug-resistant (MDR) M. tuberculosis strain. 18 As a con tinuation of this research, we have herein obtained a number of novel purine and 2-amino purine conjugates, in which the frag ment of (S)-aspartic or (S)-glu tamic acid is attached to C-6 of the purine ring system via 1,2-ethylenediamine residue (compounds 2a-d) and have studied their antimycobacterial activity against M. tuberculosis H 37 Rv and other strains.

Physical Review A, 2018

We present the first NMR implementation of a scheme for selective and efficient quantum process t... more We present the first NMR implementation of a scheme for selective and efficient quantum process tomography without ancilla. We generalize this scheme such that it can be implemented efficiently using only a set of measurements involving product operators. The method allows us to estimate any element of the quantum process matrix to a desired precision, provided a set of quantum states can be prepared efficiently. Our modified technique requires fewer experimental resources as compared to the standard implementation of selective and efficient quantum process tomography, as it exploits the special nature of NMR measurements to allow us to compute specific elements of the process matrix by a restrictive set of subsystem measurements. To demonstrate the efficacy of our scheme, we experimentally tomograph the processes corresponding to 'no operation', a controlled-NOT (CNOT), and a controlled-Hadamard gate on a two-qubit NMR quantum information processor, with high fidelities.