Physics
Permanent URI for this community
Browse
Browsing Physics by Issue Date
Now showing 1 - 20 of 93
Results Per Page
Sort Options
Item Open Access Thermodynamic and holographic information dual to volume(Eur. Phys. J., 2018) Momeni, Davood; Faizal, Mir; Alsaleh, Salwa; Alasfar, Lina; Myrzakul, Aizhan; Myrzakulov, RatbayIn this paper, we will analyze the connection between the fidelity susceptibility, the holographic complexity and the thermodynamic volume. We will regularize the fidelity susceptibility and the holographic complexity by subtracting the contribution of the background AdS spacetime from the deformation of the AdS spacetime. It will be demonstrated that this regularized fidelity susceptibility has the same behavior as the thermodynamic volume and that the regularized complexity has a very different behavior....Item Open Access Quantum compiling with diffusive sets of gates(Nazarbayev University School of Sciences and Humanities, 2018-01-15) Akulin, Vladimir M.; Mandilara, Aikaterini; Zhiyenbayev, YertayGiven a set of quantum gates and a target unitary operation, the most elementary task of quantum compiling is the identification of a sequence of the gates that approximates the target unitary to a determined precision ε. The Solovay-Kitaev theorem provides an elegant solution which is based on the construction of successively tighter “nets” around unity comprised of successively longer sequences of gates. The procedure for the construction of the nets, according to this theorem, requires accessibility to the inverse of the gates as well. In this work, we propose a method for constructing nets around unity without this requirement. The algorithmic procedure isapplicable to sets of gates which are diffusive enough, in the sense that sequences of moderate length cover the space of unitary matrices in a uniform way. We prove that the number of gates sufficient for reaching a precision ε scales as log(1/ε) log 3/ log 2 while the precompilation time is increased as compared to that of the Solovay-Kitaev algorithm by the exponential factor 3/2.Item Open Access Giant Tortoise Coordinate(Nazarbayev University School of Sciences and Humanities, 2018-01-24) Good, Michael R. R.; Myrzakul, Aizhan; Yelshibekov, Khalykbek; Ong, Yen ChinThe giant tortoise coordinate is a moving mirror inspired generalization of the ReggeWheeler counterpart that demonstrates a unitary evaporating black hole emitting a total finite energy.Item Open Access Zeeman gyrotropic scatterers: Resonance splitting, anomalous scattering, and embedded eigenstates(Nanomaterials and Nanotechnology, 2018-09-03) Valagiannopoulos, Constantinos; Gangaraj, S Ali Hassani; Monticone, FrancescoAnomalous scattering effects (invisibility, superscattering, Fano resonances, etc) enabled by complex media and metamaterials have been the subject of intense efforts in the past couple of decades. In this article, we present a full analysis of the unusual and extreme scattering properties of an important class of complex scatterers, namely, gyrotropic cylindrical bodies, including both homogeneous and core–shell configurations....Item Open Access Dust spectrum and polarisation at 850 µm in the massive IRDC G035.39-00.33(Astronomy & Astrophysics, 2018-11-23) Juvela, Mika; Guillet, Vincent; Liu, Tie; Ristorcelli, Isabelle; Pelkonen, Veli-Matti; Alina, Dana; Bronfman, Leonardo; Eden, David J.; Kim, Kee Tae; Koch, Patrick M.; Kwon, Woojin; Lee, Chang Won; Malinen, Johanna; Micelotta, Elisabetta; Montillaud, Julien; Rawlings, Mark G.; Sanhueza, Patricio; Soam, Archana; Traficante, Alessio; Ysard, Nathalie; Zhang, Chuan-PengContext. The sub-millimetre polarisation of dust emission from star-forming clouds carries information on grain properties and on the effects that magnetic fields have on cloud evolution. Aims. Using observations of a dense filamentary cloud G035.39-00.33, we aim to characterise the dust emission properties and the variations of the polarisation fraction.Item Open Access FINITE THERMAL PARTICLE CREATION OF CASIMIR LIGHT(Modern Physics Letters A, 2019) Good, Michael R. R.; Linder, Eric V.; Wilczek, FrankA new solution for an analytic spectrum of particle creation by an accelerating mir ror (dynamical Casimir effect) is given. It is the first model to simultaneously radiate thermally and emit a finite number of particles.Item Open Access Data Acquisition System for Microwave Kinetic Inductance Detectors(IOP PUBLISHING LTD, 2019) Bekbalanova, Marzhan; Shafiee, Mehdi; Kizheppatt, Vipin; Kazykenov, Zhaksylyk; Alzhanov, Baurzhan; Smoot, George F.; Grossan, BruceEnergetic Cosmos Laboratory is developing Kinetic Inductance Detectors (MKID) for mm/submm astronomy purposes. In order to measure the instantaneous resonance frequency and dissipation of superconducting microresonators of the MKID arrays, we have developed a data acquisition system with emphasis on precision, readout speed and digital processing capabilities. We use IQ mixer to down convert the MKIDs signal in the range of 20-80 MHz, then digitize them by 250 MSPS ADC. Processed data at FPGA-Kintex 7 will be transferred to the PC for further analysis by the rate of 10 Gbit/sec. In this report, we describe the technical details and the algorithm we developed.Item Open Access Statistical analysis of the interplay between interstellar magnetic fields and filaments hosting Planck Galactic cold clumps(OXFORD UNIV PRESS, 2019-02) Alina, D.; Ristorcelli, I.; Montier, L.; Abdikamalov, E.; Juvela, M.; Ferriere, K.; Bernard, J. Ph.; Micelotta, E. R.We present a statistical study of the relative orientation in the plane of the sky between interstellar magnetic fields and filaments hosting cold clumps. For the first time, we consider both the density of the environment and the density contrast between the filaments and their environment. Moreover, we geometrically distinguish between the clumps and the remaining portions of the filaments. We infer the magnetic field orientations in the filaments and in their environment from the Stokes parameters,1 assuming optically thin conditions. Thus, we analyse the relative orientations between filaments, embedded clumps, internal and background magnetic fields, depending on their environment and evolutionary stages. We recover the previously observed trend for filaments in low column density environments to be aligned parallel to the background magnetic field; however, we find that this trend is significant only for low-contrast filaments, whereas high-contrast filaments tend to be randomly orientated with respect to the background magnetic field. Filaments in high column density environments do not globally show any preferential orientation, although low-contrast filaments alone tend to have perpendicular relative orientation with respect to the background magnetic field. For a subsample of nearby filaments, for which volume densities can be derived, we find a clear transition in the relative orientation with increasing density, at nH ∼ 103 cm−3, changing from mostly parallel to mostly perpendicular in the off-clump portions of filaments and from even to bimodal in clumps. Our results confirm a strong interplay between interstellar magnetic fields and filaments during their formation and evolution.Item Open Access Antiresonances and Ultrafast Resonances in a Twin Photonic Oscillator(Institute of Electrical and Electronics Engineers, 2019-02) Kominis, Yannis; Choquette, Kent D.; Bountis, Anastassios; Kovanis, VassiliosWe consider the properties of the small-signal modulation response of symmetry-breaking phase-locked states of twin coupled semiconductor lasers. The extended stability and the varying asymmetry of these modes allows for the introduction of a rich set of interesting modulation response features, such as sharp resonances and antiresonances as well as efficient modulation at very high frequencies exceeding the free running relaxation frequencies by orders of magnitude.Item Restricted SCOPE: SCUBA-2 Continuum Observations of Pre-protostellar Evolution – survey description and compact source catalogue(Oxford University Press, 2019-02-26) Alina, Dana; Eden, D. J.; Liu, Tie; Kim, Kee-Tae; Juvela, M.; Liu, S. Y.; Tatematsu, K.; Di Francesco, J.; Wang, K.; Wu, Y.; Thompson, M. A.; Fuller, G. A.; Li, Di; Ristorcelli, I.; Kang, Sung-ju; Hirano, N.; Johnstone, D.; Lin, Y.; He, J. H.; Koch, P. M.; Sanhueza, Patricio; Qin, S. L.; Zhang, Q.; Goldsmith, P. F.; Evans, N. J.; Yuan, J.; Zhang, C. P.; White, G. J.; Choi, Minho; Lee, Chang Won; Toth, L. V.; Mairs, S.; Yi, H. W.; Tang, M.; Soam, A.; Peretto, N.; Samal, M. R.; Fich, M.; Parsons, H.; Malinen, J.; Bendo, G. J.; Rivera-Ingraham, A.; Liu, H. L.; Wouterloot, J.; Li, P. S.; Qian, L.; Rawlings, J.; Rawlings, M. G.; Feng, S.; Wang, B.; Li, Dalei; Liu, M.; Luo, G.; Marston, A. P.; Pattle, K. M.; Pelkonen, V. M.; Rigby, A. J.; Zahorecz, S.; Zhang, G.; Bogner, R.; Aikawa, Y.; Akhter, S.; Alina, D.; Bell, G.; Bernard, J. P.; Blain, A.; Bronfman, L.; Byun, D. Y.; Chapman, S.; Chen, H. R.; Chen, M.; Chen, W. P.; Chen, X.; Chen, Xuepeng; Chrysostomou, A.; Chu, Y. H.; Chung, E. J.; Cornu, D.; Cosentino, G.; Cunningham, M. R.; Demyk, K.; Drabek-Maunder, E.; Doi, Y.; Eswaraiah, C.; Falgarone, E.; Feher, O.; Fraser, H.; Friberg, P.; Garay, G.; Ge, J. X.; Gear, W. K.; Greaves, J.; Guan, X.; Harvey-Smith, L.; Hasegawa, T.; He, Y.; Henkel, C.; Hirota, T.; Holland, W.; Hughes, A.; Jarken, E.; Ji, T. G.; Jimenez-Serra, I.; Kang, M.; Kawabata, K. S.; Kim, Gwanjeong; Kim, Jungha; Kim, Jongsoo; Kim, S.; Koo, B. C.; Kwon, Woojin; Kuan, Y. J.; Lacaille, K. M.; Lai, S. P.; Lee, C. F.; Lee, J. E.; Lee, Y. U.; Li, H.; Lo, N.; Lopez, J. A.; Lu, X.; Lyo, A. R.; Mardones, D.; McGehee, P.; Meng, F.; Montier, L.; Montillaud, J.; Moore, T. J.; Morata, O.; Moriarty-Schieven, G. H.; Ohashi, S.; Pak, S.; Park, Geumsook; Paladini, R.; Pech, G.; Qiu, K.; Ren, Z. Y.; Richer, J.; Sakai, T.; Shang, H.; Shinnaga, H.; Stamatellos, D.; Tang, Y. W.; Traficante, A.; Vastel, C.; Viti, S.; Walsh, A.; Wang, H.; Wang, J.; Ward-Thompson, D.; Whitworth, A.; Wilson, C. D.; Xu, Y.; Yang, J.; Yuan, Y. L.; Yuan, L.; Zavagno, A.; Zhang, C.; Zhang, G.; Zhang, H. W.; Zhou, C.; Zhou, J.; Zhu, L.; Zuo, P.We present the first release of the data and compact-source catalogue for the JCMT Large Program SCUBA-2 Continuum Observations of Pre-protostellar Evolution (SCOPE). SCOPE consists of 850 μm continuum observations of 1235 Planck Galactic Cold Clumps (PGCCs) made with the Submillimetre Common-User Bolometer Array 2 on the James Clerk Maxwell Telescope. These data are at an angular resolution of 14.4 arcsec, significantly improving upon the 353 GHz resolution of Planck at 5 arcmin, and allowing for a catalogue of 3528 compact sources in 558 PGCCs. We find that the detected PGCCs have significant sub-structure, with 61 per cent of detected PGCCs having three or more compact sources, with filamentary structure also prevalent within the sample. A detection rate of 45 per cent is found across the survey, which is 95 per cent complete to Planck column densities of NH2 > 5 × 1021 cm−2. By positionally associating the SCOPE compact sources with young stellar objects, the star formation efficiency, as measured by the ratio of luminosity to mass, in nearby clouds is found to be similar to that in the more distant Galactic Plane, with the column density distributions also indistinguishable from each other.Item Open Access Extended logotropic fluids as unified dark energy models(Springer, 2019-04) Boshkayev, Kuantay; D'Agostino, Rocco; Luongo, OrlandoWe study extended classes of logotropic fluids as unified dark energy models. Under the hypothesis of the Anton–Schmidt scenario, we consider a universe obeying a single fluid model with a logarithmic equation of state. We investigate the thermodynamic and dynamical consequences of an extended version of the Anton–Schmidt cosmic fluids. Specifically, we expand the Anton–Schmidt pressure in the infrared regime. The low-energy case becomes relevant for the universe as regards acceleration without any cosmological constant. We therefore derive the effective representation of our fluid in terms of a Lagrangian depending on the kinetic term only. We analyze both the relativistic and the non-relativistic limits. In the non-relativistic limit we construct both the Hamiltonian and the Lagrangian in terms of density ρ and scalar field ϑ, whereas in the relativistic case no analytical expression for the Lagrangian can be found. Thus, we obtain the potential as a function of ρ, under the hypothesis of an irrotational perfect fluid. We demonstrate that the model represents a natural generalization of logotropic dark energy models. Finally, we analyze an extended class of generalized Chaplygin gas models with one extra parameter β. Interestingly, we find that the Lagrangians of this scenario and the pure logotropic one coincide in the non-relativistic regime.Item Open Access Horizon-T Experiment Upgrade and Calibration of New Detection Points(Nazarbayev University School of Sciences and Humanities, 2019-06-12) Beznosko, Dmitriy; Beremkulov, Т.; Iakovlev, A.; Jakupov, S; Turganov, D.; Tussipzhan, A; Uakhitov, T.; Vildanova, M.I.; Yeltokov, A; Zhukov, V.V.In March of 2018, after the completion of the Physics Run 2, an upgrade has been installed at an innovative detector system Horizon-T, with the upgraded version now called Horizon-10T. It was constructed to study Extensive Air Showers (EAS) in the energy range above 10^16 eV coming from a wide range of zenith angles (0 - 85 degrees). The system is located at Tien Shan high-altitude Science Station of Lebedev Physical Institute of the Russian Academy of Sciences at approximately 3340 meters above the sea level. After this upgrade, the detector consists of ten charged particle detection points separated by the distance up to 1.3 kilometer as well as optical detector to view the Vavilov-Cherenkov light from the EAS. Each detector connects to the Data Acquisition system via cables. The calibration of the time delay for each cable including newly installed ones and the signal attenuation is provided in this article as well as the description of the newly installed detection points and their MIP response values.Item Open Access Conformal High-K Dielectric Coating of Suspended Single-Walled Carbon Nanotubes by Atomic Layer Deposition(MDPI, 2019-08) Kemelbay, Aidar; Tikhonov, Alexander; Aloni, Shaul; Kuykendall, Tevye R.As one of the highest mobility semiconductor materials, carbon nanotubes (CNTs) have been extensively studied for use in field effect transistors (FETs). To fabricate surround-gate FETs— which offer the best switching performance—deposition of conformal, weakly-interacting dielectric layers is necessary. This is challenging due to the chemically inert surface of CNTs and a lack of nucleation sites—especially for defect-free CNTs. As a result, a technique that enables integration of uniform high-k dielectrics, while preserving the CNT’s exceptional properties is required. In this work, we show a method that enables conformal atomic layer deposition (ALD) of high-k dielectrics on defect-free CNTs. By depositing a thin Ti metal film, followed by oxidation to TiO2 under ambient conditions, a nucleation layer is formed for subsequent ALD deposition of Al2O3. The technique is easy to implement and is VLSI-compatible. We show that the ALD coatings are uniform, continuous and conformal, and Raman spectroscopy reveals that the technique does not induce defects in the CNT. The resulting bilayer TiO2/Al2O3 thin-film shows an improved dielectric constant of 21.7 and an equivalent oxide thickness of 2.7 nm. The electrical properties of back-gated and top-gated devices fabricated using this method are presented.Item Open Access Ground and excited S-1 states of the beryllium atom(American Physical Society, 2019-09-04) Hornyak, Istvan; Adamowicz, Ludwik; Bubin, SergiyBenchmark calculations of the total and transition energies of the four lowest S-1 states of the beryllium atom are performed. The computational approach is based on variational calculations with finite mass of the nucleus. All-particle explicitly correlated Gaussian (ECG) functions are used to expand the total non-Born-Oppenheimer nonrelativistic wave functions and the ECG exponential parameters are optimized using the standard variational method. The leading relativistic and quantum electrodynamics energy corrections are calculated using the first-order perturbation theory. A comparison of the experimental transition frequencies with the ones calculated in this work shows excellent agreement. The deviations of 0.02-0.09 cm(-1) are well within the estimated error limits for the experimental values.Item Open Access Ground and excited S-1 states of the beryllium atom(American Physical Society, 2019-09-04) Hornyak, Istvan; Adamowicz, Ludwik; Bubin, SergiyBenchmark calculations of the total and transition energies of the four lowest S1 states of the beryllium atom are performed. The computational approach is based on variational calculations with finite mass of the nucleus. All-particle explicitly correlated Gaussian (ECG) functions are used to expand the total non-Born-Oppenheimer nonrelativistic wave functions and the ECG exponential parameters are optimized using the standard variational method. The leading relativistic and quantum electrodynamics energy corrections are calculated using the first-order perturbation theory. A comparison of the experimental transition frequencies with the ones calculated in this work shows excellent agreement. The deviations of 0.02-0.09cm-1 are well within the estimated error limits for the experimental values.Item Open Access The geometry of the magnetic field in the central molecular zone measured by PILOT(ASTRONOMY & ASTROPHYSICS, 2019-09-23) A., Mangilli; J., Aumont; J-Ph, Bernard; A., Buzzelli; G., de Gasperis; J. B., Durrive; K., Ferriere; G., Foenard; A., Hughes; A., LacourtWe present the first far infrared (FIR) dust emission polarization map covering the full extent of Milky Way’s central molecular zone (CMZ). The data, obtained with the PILOT balloon-borne experiment, covers the Galactic center region −2 ◦ < ` < 2◦, −4◦ < b < 3◦ at a wavelength of 240 µm and an angular resolution of 2.20 . From our measured dust polarization angles, we infer a magnetic field orientation projected onto the plane of the sky (POS) that is remarkably ordered over the full extent of the CMZ, with an average tilt angle of '22◦ clockwise with respect to the Galactic plane. Our results confirm previous claims that the field traced by dust polarized emission is oriented nearly orthogonally to the field traced by GHz radio synchrotron emission in the Galactic center region. The observed field structure is globally compatible with the latest Planck polarization data at 353 and 217 GHz. Upon subtraction of the extended emission in our data, the mean field orientation that we obtain shows good agreement with the mean field orientation measured at higher angular resolution by the JCMT within the 20 and 50 km s−1 molecular clouds. We find no evidence that the magnetic field orientation is related to the 100 pc twisted ring structure within the CMZ. The low polarization fraction in the Galactic center region measured with Planck at 353 GHz combined with a highly ordered projected field orientation is unusual. This feature actually extends to the whole inner Galactic plane. We propose that it could be caused by the increased number of turbulent cells for the long lines of sight towards the inner Galactic plane or to dust properties specific to the inner regions of the Galaxy. Assuming equipartition between magnetic pressure and ram pressure, we obtain magnetic field strength estimates of the order of 1 mG for several CMZ molecular clouds.Item Open Access Magnetic Fields in the Infrared Dark Cloud G34.43+0.24(IOP PUBLISHING, 2019-09-24) Soam, Archana; Liu, Tie; Andersson, B-G; Lee, Chang Won; Liu, Junhao; Juvela, Mika; Li, Pak Shing; Goldsmith, Paul F.; Zhang, Qizhou; Koch, Patrick M.; Kim, Kee-Tae; Qiu, Keping; Evans, Neal J., II; Johnstone, Doug; Thompson, Mark; Ward-Thompson, Derek; Di Francesco, James; Tang, Ya-Wen; Montillaud, Julien; Kim, Gwanjeong; Mairs, Steve; Sanhueza, Patricio; Kim, Shinyoung; Berry, David; Gordon, Michael S.; Tatematsu, Ken'ichi; Liu, Sheng-Yuan; Pattle, Kate; Eden, David; McGehee, Peregrine M.; Wang, Ke; Ristorcelli, I.; Graves, Sarah F.; Alina, Dana; Lacaille, Kevin M.; Montier, Ludovic; Park, Geumsook; Kwon, Woojin; Chung, Eun Jun; Pelkonen, Veli-Matti; Micelotta, Elisabetta R.; Saajasto, Mika; Fuller, GaryWe present the B-fields mapped in IRDC G34.43+0.24 using 850 mu m polarized dust emission observed with the POL-2 instrument at the James Clerk Maxwell telescope. We examine the magnetic field geometries and strengths in the northern, central, and southern regions of the filament. The overall field geometry is ordered and aligned closely perpendicular to the filament's main axis, particularly in regions containing the central clumps MM1 and MM2, whereas MM3 in the north has field orientations aligned with its major axis. The overall field orientations are uniform at large (POL-2 at 14 '' and SHARP at 10 '') to small scales (TADPOL at 2 ''.5 and SMA at 1 ''.5) in the MM1 and MM2 regions. SHARP/CSO observations in MM3 at 350 mu m from Tang et al. show a similar trend as seen in our POL-2 observations. TADPOL observations demonstrate a well-defined field geometry in MM1/MM2 consistent with MHD simulations of accreting filaments. We obtained a plane-of-sky magnetic field strength of 470 +/- 190 mu G, 100 +/- 40 mu G, and 60 +/- 34 mu G in the central, northern, and southern regions of G34, respectively, using the updated Davis-Chandrasekhar-Fermi relation. The estimated value of field strength, combined with column density and velocity dispersion values available in the literature, suggests G34 to be marginally critical with criticality parameter lambda values 0.8 +/- 0.4, 1.1 +/- 0.8, and 0.9 +/- 0.5 in the central, northern, and southern regions, respectively. The turbulent motions in G34 are sub-AlfvEnic with Alfvenic Mach numbers of 0.34 +/- 0.13, 0.53 +/- 0.30, and 0.49 +/- 0.26 in the three regions. The observed aligned B-fields in G34.43+0.24 are consistent with theoretical models suggesting that B-fields play an important role in guiding the contraction of the cloud driven by gravity.Item Open Access The Erez-Rosen Solution Versus the Hartle-Thorne Solution(MDPI, 2019-10) Boshkayev, Kuantay; Quevedo, Hernando; Nurbakyt, Gulmira; Malybayev, Algis; Urazalina, AinurIn this work, we investigate the correspondence between the Erez–Rosen and Hartle–Thorne solutions. We explicitly show how to establish the relationship and find the coordinate transformations between the two metrics. For this purpose the two metrics must have the same approximation and describe the gravitational field of static objects. Since both the Erez–Rosen and the Hartle–Thorne solutions are particular solutions of a more general solution, the Zipoy–Voorhees transformation is applied to the exact Erez–Rosen metric in order to obtain a generalized solution in terms of the Zipoy–Voorhees parameter δ=1+sq . The Geroch–Hansen multipole moments of the generalized Erez–Rosen metric are calculated to find the definition of the total mass and quadrupole moment in terms of the mass m, quadrupole q and Zipoy–Voorhees δ parameters. The coordinate transformations between the metrics are found in the approximation of ∼q. It is shown that the Zipoy–Voorhees parameter is equal to δ=1−q with s=−1 . This result is in agreement with previous results in the literature.Item Open Access Perovskite solar cells with a hybrid electrode structure(AIP Publishing, 2019-12-23) Jumabekov, Askhat; Hu, Yinghong; Adhyaksa, Gede W. P.; DeLuca, Giovanni; Simonov, Alexandr N.; Duffy, Noel W.; Reichmanis, Elsa; Bach, Udo; Docampo, Pablo; Bein, Thomas; Garnett, Erik C.; Chesman, Anthony S. R.Perovskite solar cells (PSCs) with a novel hybrid electrode structure, in which a single device can operate with either a vertical (sandwich) or lateral (back-contact) configuration of contacts, are demonstrated in this work. The hybrid structure was achieved by depositing an additional anode on top of a prefabricated back-contact PSC device, giving a final device with three electrodes—one shared cathode and two anodes. Device performances are tested and evaluated for both operation modes, and a semianalytical model along with coupled optoelectronic simulations is used to rationalize the experimental results. It is determined that due to the intrinsically narrow depletion region near the contact interfaces, the charge collection efficiency in the back-contact device structure appears to be significantly lower compared to the sandwich device structure. This finding provides an insight into the cause of the performance disparity between these two architectures.Item Open Access THE IMPACT OF PROGENITOR ASYMMETRIES ON THE NEUTRINO-DRIVEN CONVECTION IN CORE-COLLAPSE SUPERNOVAE(arxiv, 2020) Kazeroni, R´emi; Abdikamalov, ErnazarThe explosion of massive stars in core-collapse supernovae may be aided by the con vective instabilities that develop in their innermost nuclear burning shells. The re sulting fluctuations support the explosion by generating additional turbulence behind the supernova shock. It was suggested that the buoyant density perturbations aris ing from the interaction of the pre-collapse asymmetries with the shock may be the primary contributor to the enhancement of the neutrino-driven turbulent convection in the post-shock region. Employing three-dimensional numerical simulations of a toy model, we investigate the impact of such density perturbations on the post-shock tur bulence. We consider a wide range of perturbation parameters. The spatial scale and the amplitude of the perturbations are found to be of comparable importance. The turbulence is particularly enhanced when the perturbation frequency is close to that of the convective turnovers in the gain region. Our analysis confirms that the buoyant density perturbations is indeed the main source of the additional turbulence in the gain region, validating the previous order-of-magnitude estimates.